An access control entry. An access control entry is one element in an ACL. An access control entry is a three-tuple that describes three things: an action (one of either Allow or Deny), a principal (a string describing a user or group), and a permission. For example the ACE, (Allow, 'bob', 'read') is a member of an ACL that indicates that the principal bob is allowed the permission read against the resource the ACL is attached to.


An access control list. An ACL is a sequence of ACE tuples. An ACL is attached to a resource instance. An example of an ACL is [ (Allow, 'bob', 'read'), (Deny, 'fred', 'write')]. If an ACL is attached to a resource instance, and that resource is findable via the context resource, it will be consulted any active security policy to determine whether a particular request can be fulfilled given the authentication information in the request.


Represents a pending configuration statement generated by a call to a configuration directive. The set of pending configuration actions are processed when pyramid.config.Configurator.commit() is called.


A Python distribution that uses Pyramid's extensibility to plug into a Pyramid application and provide extra, configurable services.

Agendaless Consulting

A consulting organization formed by Paul Everitt, Tres Seaver, and Chris McDonough.

See also

See also Agendaless Consulting.


Akhet is a Pyramid library and demo application with a Pylons-like feel. It's most known for its former application scaffold, which helped users transition from Pylons and those preferring a more Pylons-like API. The scaffold has been retired but the demo plays a similar role.


Alembic is a lightweight database migration tool for usage with the SQLAlchemy Database Toolkit for Python.

application registry

A registry of configuration information consulted by Pyramid while servicing an application. An application registry maps resource types to views, as well as housing other application-specific component registrations. Every Pyramid application has one (and only one) application registry.


Any file contained within a Python package which is not a Python source code file.

asset descriptor

An instance representing an asset specification provided by the pyramid.path.AssetResolver.resolve() method. It supports the methods and attributes documented in pyramid.interfaces.IAssetDescriptor.

asset specification

A colon-delimited identifier for an asset. The colon separates a Python package name from a package subpath. For example, the asset specification my.package:static/baz.css identifies the file named baz.css in the static subdirectory of the my.package Python package. See Understanding Asset Specifications for more info.


The act of determining that the credentials a user presents during a particular request are "good". Authentication in Pyramid is performed via an authentication policy.

authentication policy

An authentication policy in Pyramid terms is a bit of code which has an API which determines the current principal (or principals) associated with a request.

Deprecated since version 2.0: Authentication policies have been deprecated in favor of a security policy.


The act of determining whether a user can perform a specific action. In pyramid terms, this means determining whether, for a given resource, any principal (or principals) associated with the request have the requisite permission to allow the request to continue. Authorization in Pyramid is performed via its authorization policy.

authorization policy

An authorization policy in Pyramid terms is a bit of code which has an API which determines whether or not the principals associated with the request can perform an action associated with a permission, based on the information found on the context resource.

Deprecated since version 2.0: Authorization policies have been deprecated in favor of a security policy.


A collection of tools for internationalizing Python applications. Pyramid does not depend on Babel to operate, but if Babel is installed, additional locale functionality becomes available to your application.

cache busting

A technique used when serving a cacheable static asset in order to force a client to query the new version of the asset. See Cache Busting for more information.


chameleon is an attribute language template compiler which supports the ZPT templating specification. It is written and maintained by Malthe Borch. It has several extensions, such as the ability to use bracketed (Mako-style) ${name} syntax. It is also much faster than the reference implementation of ZPT. Pyramid offers Chameleon templating out of the box in ZPT and text flavors.


An operation applied to a configurator. A commit checks for conflicts in configuration declarations, and if none are found applies all pending actions. It is possible, although not necessarily recommended, to invoke commits using pyramid.config.Configurator.commit() to manually resolve configuration conflicts.

configuration declaration

An individual method call made to a configuration directive, such as registering a view configuration (via the add_view() method of the configurator) or route configuration (via the add_route() method of the configurator). A set of configuration declarations is also implied by the configuration decoration detected by a scan of code in a package.

configuration decoration

Metadata implying one or more configuration declaration invocations. Often set by configuration Python decorator attributes, such as pyramid.view.view_config, aka @view_config.

configuration directive

A method of the Configurator which causes a configuration action to occur. The method pyramid.config.Configurator.add_view() is a configuration directive, and application developers can add their own directives as necessary (see Adding Methods to the Configurator via add_directive).


An object used to do configuration declaration within an application. The most common configurator is an instance of the pyramid.config.Configurator class.

conflict resolution

Pyramid attempts to resolve ambiguous configuration statements made by application developers via automatic conflict resolution. Automatic conflict resolution is described in Automatic Conflict Resolution. If Pyramid cannot resolve ambiguous configuration statements, it is possible to manually resolve them as described in Manually Resolving Conflicts.

console script

A script written to the bin (on Unix, or Scripts on Windows) directory of a Python installation or virtual environment as the result of running pip install or pip install -e ..


A function returning a Pyramid WSGI application. Every Pyramid application has a single constructor function named main. It returns a Pyramid router generated by a configurator, and is written by you. The Pyramid constructor is the application's entry point.


A resource in the resource tree that is found during traversal or URL dispatch based on URL data; if it's found via traversal, it's usually a resource object that is part of a resource tree; if it's found via URL dispatch, it's an object manufactured on behalf of the route's "factory". A context resource becomes the subject of a view, and often has security information attached to it. See the Traversal chapter and the URL Dispatch chapter for more information about how a URL is resolved to a context resource.

context manager

A context manager is an object that defines the runtime context to be established when executing a with statement in Python. The context manager handles the entry into, and the exit from, the desired runtime context for the execution of the block of code. Context managers are normally invoked using the with statement, but can also be used by directly invoking their methods. Pyramid adds context managers for pyramid.config.Configurator, pyramid.interfaces.IRouter.request_context(), pyramid.paster.bootstrap(), pyramid.scripting.prepare(), and pyramid.testing.testConfig(). See also the Python documentation for With Statement Context Managers and PEP 343.


A command-line utility that creates projects from cookiecutters (project templates), e.g., creating a Python package project from a Python package project template.

New in version 1.8: Added cookiecutter support.

Changed in version 1.10: Merged features from pyramid-cookiecutter-alchemy and pyramid-cookiecutter-zodb into the single cookiecutter to rule them all, pyramid-cookiecutter-starter.

Deprecated since version 1.10: pyramid-cookiecutter-alchemy and pyramid-cookiecutter-zodb are no longer supported. Use pyramid-cookiecutter-starter going forward.


A measurement of code coverage, usually expressed as a percentage of which lines of code have been executed over which lines are executable, typically run during test execution.


The C implementation of the Python language. This is the reference implementation that most people refer to as simply "Python"; Jython, Google's App Engine, and PyPy are examples of non-C based Python implementations.

CSRF storage policy

A utility that implements pyramid.interfaces.ICSRFStoragePolicy which is responsible for allocating CSRF tokens to a user and verifying that a provided token is acceptable.

declarative configuration

The configuration mode in which you use the combination of configuration decoration and a scan to configure your Pyramid application.


A wrapper around a Python function or class which accepts the function or class as its first argument and which returns an arbitrary object. Pyramid provides several decorators, used for configuration and return value modification purposes.

See also

See also PEP 318.

Default Locale Name

The locale name used by an application when no explicit locale name is set. See Localization-Related Deployment Settings.

default permission

A permission which is registered as the default for an entire application. When a default permission is in effect, every view configuration registered with the system will be effectively amended with a permission argument that will require that the executing user possess the default permission in order to successfully execute the associated view callable.

See also

See also Setting a Default Permission.

default root factory

If an application does not register a root factory at Pyramid configuration time, a default root factory is used to created the default root object. Use of the default root object is useful in application which use URL dispatch for all URL-to-view code mappings, and does not (knowingly) use traversal otherwise.

Default view

The default view of a resource is the view invoked when the view name is the empty string (''). This is the case when traversal exhausts the path elements in the PATH_INFO of a request before it returns a context resource.

Deployment settings

Deployment settings are settings passed to the Configurator as a settings argument. These are later accessible via a request.registry.settings dictionary in views or as config.registry.settings in configuration code. Deployment settings can be used as global application values.


The unique identifier of an action.


Setuptools / Python packaging terminology. A file representing an installable library or application. Distributions are usually archives that have the suffix of .whl, .tar.gz, or .zip. Distributions are the target of packaging-related commands such as pip install.


The standard system for packaging and distributing Python packages. See for more information. Setuptools is actually an extension of the Distutils.


A full-featured Python web framework.

domain model

Persistent data related to your application. For example, data stored in a relational database. In some applications, the resource tree acts as the domain model.

dotted Python name

A reference to a Python object by name using a string, in the form Often used in Pyramid and Setuptools configurations. A variant is used in dotted names within configurator method arguments that name objects (such as the "add_view" method's "view" and "context" attributes): the colon (:) is not used; in its place is a dot.

entry point

A Setuptools indirection, defined within a Setuptools distribution (usually in or setup.cfg). It is usually a name which refers to a function somewhere in a package which is held by the distribution.


An object broadcast to zero or more subscriber callables during normal Pyramid system operations during the lifetime of an application. Application code can subscribe to these events by using the subscriber functionality described in Using Events.

exception response

A response that is generated as the result of a raised exception being caught by an exception view.

Exception view

An exception view is a view callable which may be invoked by Pyramid when an exception is raised during request processing. See Custom Exception Views for more information.

execution policy

A policy which wraps the router by creating the request object and sending it through the request pipeline. See pyramid.config.Configurator.set_execution_policy.

falsey string

A string represeting a value of False. Acceptable values are f, false, n, no, off and 0.

finished callback

A user-defined callback executed by the router unconditionally at the very end of request processing . See Using Finished Callbacks.

Forbidden view

An exception view invoked by Pyramid when the developer explicitly raises a pyramid.httpexceptions.HTTPForbidden exception from within view code or root factory code, or when the view configuration and authorization policy found for a request disallows a particular view invocation. Pyramid provides a default implementation of a forbidden view; it can be overridden. See Changing the Forbidden View.


An XML templating language by Christopher Lenz.


The GNU gettext library, used by the Pyramid translation machinery.

global state

A set of values that are available to the entirety of a program.

Google App Engine

Google App Engine (aka "GAE") is a Python application hosting service offered by Google. Pyramid runs on GAE.


A web framework based on Zope 3.


Aka gunicorn, a fast WSGI server that runs on Unix under Python 2.6+ or Python 3.4+. See for detailed information.

HTTP Exception

The set of exception classes defined in pyramid.httpexceptions. These can be used to generate responses with various status codes when raised or returned from a view callable.

See also

See also HTTP Exceptions.


An identity is an object identifying the user associated with the current request. The object can be of any shape, such as a simple ID string or an ORM object.


In Python, a value is immutable if it cannot be changed. The Python str, int, and tuple data types are all immutable.

imperative configuration

The configuration mode in which you use Python to call methods on a Configurator in order to add each configuration declaration required by your application.

import time

In Python, the moment when a module is referred to in an import statement. At this moment, all statements in that module at the module scope (at the left margin) are executed. It is a bad design decision to put statements in a Python module that have side effects at import time.


A Zope interface object. In Pyramid, an interface may be attached to a resource object or a request object in order to identify that the object is "of a type". Interfaces are used internally by Pyramid to perform view lookups and other policy lookups. The ability to make use of an interface is exposed to an application programmers during view configuration via the context argument, the request_type argument and the containment argument. Interfaces are also exposed to application developers when they make use of the event system. Fundamentally, Pyramid programmers can think of an interface as something that they can attach to an object that stamps it with a "type" unrelated to its underlying Python type. Interfaces can also be used to describe the behavior of an object (its methods and attributes), but unless they choose to, Pyramid programmers do not need to understand or use this feature of interfaces.


The act of creating software with a user interface that can potentially be displayed in more than one language or cultural context. Often shortened to "i18n" (because the word "internationalization" is I, 18 letters, then N).

See also

See also Localization.


An object which implements the attributes and methods described in pyramid.interfaces.IIntrospectable. Introspectables are used by the introspector to display configuration information about a running Pyramid application. An introspectable is associated with a action by virtue of the pyramid.config.Configurator.action() method.


An object with the methods described by pyramid.interfaces.IIntrospector that is available in both configuration code (for registration) and at runtime (for querying) that allows a developer to introspect configuration statements and relationships between those statements.


A text templating language by Armin Ronacher.


A popular Javascript library.


JavaScript Object Notation is a data serialization format.


A Python implementation written for the Java Virtual Machine.


An ordered sequence of objects based on a "location -aware" resource. The lineage of any given resource is composed of itself, its parent, its parent's parent, and so on. The order of the sequence is resource-first, then the parent of the resource, then its parent's parent, and so on. The parent of a resource in a lineage is available as its __parent__ attribute.


A package by Wichert Akkerman which provides the pot-create command to extract translateable messages from Python sources and Chameleon ZPT template files.

Locale Name

A string like en, en_US, de, or de_AT which uniquely identifies a particular locale.

Locale Negotiator

An object supplying a policy determining which locale name best represents a given request. It is used by the pyramid.i18n.get_locale_name(), and pyramid.i18n.negotiate_locale_name() functions, and indirectly by pyramid.i18n.get_localizer(). The pyramid.i18n.default_locale_negotiator() function is an example of a locale negotiator.


The process of displaying the user interface of an internationalized application in a particular language or cultural context. Often shortened to "l10n" (because the word "localization" is L, 10 letters, then N).

See also

See also Internationalization.


An instance of the class pyramid.i18n.Localizer which provides translation and pluralization services to an application. It is retrieved via the pyramid.i18n.get_localizer() function.


The path to an object in a resource tree. See Location-Aware Resources for more information about how to make a resource object location-aware.


Mako is a template language which refines the familiar ideas of componentized layout and inheritance using Python with Python scoping and calling semantics.


The dictionary attached to the request object as request.matchdict when a URL dispatch route has been matched. Its keys are names as identified within the route pattern; its values are the values matched by each pattern name.

media type

A label representing the type of some content. A media type is a nested structure containing a top-level type and a subtype. Optionally, a media type can also contain parameters specific to the type. See RFC 6838 for more information about media types.

Message Catalog

A gettext .mo file containing translations.

Message Identifier

A string used as a translation lookup key during localization. The msgid argument to a translation string is a message identifier. Message identifiers are also present in a message catalog.


Macro Expansion for TAL, a part of ZPT which makes it possible to share common look and feel between templates.


Middleware is a WSGI concept. It is a WSGI component that acts both as a server and an application. Interesting uses for middleware exist, such as caching, content-transport encoding, and other functions. See WSGI documentation or PyPI to find middleware for your application.


mod_wsgi is an Apache module developed by Graham Dumpleton. It allows WSGI applications (such as applications developed using Pyramid) to be served using the Apache web server.


A Python source file; a file on the filesystem that typically ends with the extension .py or .pyc. Modules often live in a package.


An ordered dictionary that can have multiple values for each key. Adds the methods getall, getone, mixed, add and dict_of_lists to the normal dictionary interface. See Multidict and pyramid.interfaces.IMultiDict.


In Python, a value is mutable if it can be changed in place. The Python list and dict types are mutable. When a value is added to or removed from an instance of either, the original object remains. The opposite of mutable is immutable.

Not Found View

An exception view invoked by Pyramid when the developer explicitly raises a pyramid.httpexceptions.HTTPNotFound exception from within view code or root factory code, or when the current request doesn't match any view configuration. Pyramid provides a default implementation of a Not Found View; it can be overridden. See Changing the Not Found View.


A directory on disk which contains an file, making it recognizable to Python as a location which can be import -ed. A package exists to contain module files.


PasteDeploy is a library used by Pyramid which makes it possible to configure WSGI components together declaratively within an .ini file. It was developed by Ian Bicking.


A string that represents an action being taken against a context resource. A permission is associated with a view name and a resource type by the developer. Resources are decorated with security declarations (e.g. an ACL), which reference these tokens also. Permissions are used by the active security policy to match the view permission against the resources's statements about which permissions are granted to which principal in a context in order to answer the question "is this user allowed to do this". Examples of permissions: read, or view_blog_entries.

physical path

The path required by a traversal which resolve a resource starting from the physical root. For example, the physical path of the abc subobject of the physical root object is /abc. Physical paths can also be specified as tuples where the first element is the empty string (representing the root), and every other element is a Unicode string, e.g. ('', 'abc'). Physical paths are also sometimes called "traversal paths".

physical root

The object returned by the application root factory. Unlike the virtual root of a request, it is not impacted by Virtual Hosting: it will always be the actual object returned by the root factory, never a subobject.


The Python Packaging Authority's recommended tool for installing Python packages.


The PasteDeploy term for a single configuration of a WSGI server, a WSGI application, with a set of middleware in-between.


A module which ships with Setuptools that provides an API for addressing "asset files" within a Python package. Asset files are static files, template files, etc; basically anything non-Python-source that lives in a Python package can be considered a asset file.


plaster is a library used by Pyramid which acts as an abstraction between command-line scripts and the file format used to load the WSGI components and application settings. By default Pyramid ships with the plaster_pastedeploy library installed which provides integrated support for loading a PasteDeploy INI file.


A test which returns True or False. Two different types of predicates exist in Pyramid: a view predicate and a route predicate. View predicates are attached to view configuration and route predicates are attached to route configuration.

predicate factory

A callable which is used by a third party during the registration of a route, view, or subscriber predicates to extend the configuration system. See Adding a Custom View, Route, or Subscriber Predicate for more information.


A pregenerator is a function associated by a developer with a route. It is called by route_url() in order to adjust the set of arguments passed to it by the user for special purposes. It will influence the URL returned by route_url(). See pyramid.interfaces.IRoutePregenerator for more information.


A principal is a string representing an entity, typically a user or group. Principals are provided by an authentication policy. For example, if a user has the userid bob, and is a member of two groups named group foo and group bar, then the request might have information attached to it indicating that Bob was represented by three principals: bob, group foo and group bar.


Setuptools / Python packaging terminology. A directory on disk which contains a and / or pyproject.toml file and one or more Python packages. The project files contain metadata that allow the package(s) to be installed, distributed, and tested.


A lightweight Python web framework and a predecessor of Pyramid.


The Python Package Index, a collection of software available for Python.


PyPy is an "alternative implementation of the Python language":

Pyramid Community Cookbook

Additional, community-based documentation for Pyramid which presents topical, practical uses of Pyramid: Pyramid Community Cookbook


A Pyramid add-on which displays a helpful debug toolbar "on top of" HTML pages rendered by your application, displaying request, routing, and database information. pyramid_debugtoolbar is configured into the development.ini of all applications which use a Pyramid cookiecutter. For more information, see


A package which logs Pyramid application exception (error) information to a standard Python logger. This add-on is most useful when used in production applications, because the logger can be configured to log to a file, to Unix syslog, to the Windows Event Log, or even to email. See its documentation.


An add-on package which allows Pyramid users to create classes that are analogues of Pylons 1 "controllers". See


Jinja2 templating system bindings for Pyramid, documented at This package also includes a scaffold named pyramid_jinja2_starter, which creates an application package based on the Jinja2 templating system.


A package by Eric Rasmussen which allows you to store Pyramid session data in a Redis database. See for more information.


An add-on package to Pyramid which allows applications to be configured via ZCML. It is available on PyPI. If you use pyramid_zcml, you can use ZCML as an alternative to imperative configuration or configuration decoration.


The programming language in which Pyramid is written.

Python Packaging Authority

The Python Packaging Authority (PyPA) is a working group that maintains many of the relevant projects in Python packaging.


A serializer which converts non-Response return values from a view into a string, and ultimately into a response, usually through view configuration. Using a renderer can make writing views that require templating or other serialization, like JSON, less tedious. See Writing View Callables Which Use a Renderer for more information.

renderer factory

A factory which creates a renderer. See Adding and Changing Renderers for more information.

renderer globals

Values injected as names into a renderer by a pyramid.event.BeforeRender event.


"Repoze" is essentially a "brand" of software developed by Agendaless Consulting and a set of contributors. The term has no special intrinsic meaning. The project's website has more information. The software developed "under the brand" is available in a Subversion repository. Pyramid was originally known as repoze.bfg.


An indexing and search facility (fielded and full-text) based on zope.index. See the documentation for more information.


Zope2 CMF-like data structures and helper facilities for CA-and-ZODB-based applications useful within Pyramid applications.


Authentication middleware for WSGI applications. It can be used by Pyramid to provide authentication information.


Barebones workflow for Python apps . It can be used by Pyramid to form a workflow system.


An object that represents an HTTP request, usually an instance of the pyramid.request.Request class. See Request and Response Objects (narrative) and pyramid.request (API documentation) for information about request objects.

request factory

An object which, provided a WSGI environment as a single positional argument, returns a Pyramid-compatible request.

request type

An attribute of a request that allows for specialization of view invocation based on arbitrary categorization. The every request object that Pyramid generates and manipulates has one or more interface objects attached to it. The default interface attached to a request object is pyramid.interfaces.IRequest.


An object representing a node in the resource tree of an application. If traversal is used, a resource is an element in the resource tree traversed by the system. When traversal is used, a resource becomes the context of a view. If URL dispatch is used, a single resource is generated for each request and is used as the context resource of a view.

Resource Location

The act of locating a context resource given a request. Traversal and URL dispatch are the resource location subsystems used by Pyramid.

resource tree

A nested set of dictionary-like objects, each of which is a resource. The act of traversal uses the resource tree to find a context resource.


An object returned by a view callable that represents response data returned to the requesting user agent. It must implement the pyramid.interfaces.IResponse interface. A response object is typically an instance of the pyramid.response.Response class or a subclass such as pyramid.httpexceptions.HTTPFound. See Request and Response Objects for information about response objects.

response adapter

A callable which accepts an arbitrary object and "converts" it to a pyramid.response.Response object. See Changing How Pyramid Treats View Responses for more information.

response callback

A user-defined callback executed by the router at a point after a response object is successfully created.

See also

See also Using Response Callbacks.

response factory

An object which, provided a request as a single positional argument, returns a Pyramid-compatible response. See pyramid.interfaces.IResponseFactory.


A plain text markup format that is the defacto standard for documenting Python projects. The Pyramid documentation is written in reStructuredText.


The object at which traversal begins when Pyramid searches for a context resource (for URL Dispatch, the root is always the context resource unless the traverse= argument is used in route configuration).

root factory

The "root factory" of a Pyramid application is called on every request sent to the application. The root factory returns the traversal root of an application. It is conventionally named get_root. An application may supply a root factory to Pyramid during the construction of a Configurator. If a root factory is not supplied, the application creates a default root object using the default root factory.


A single pattern matched by the URL dispatch subsystem, which generally resolves to a root factory (and then ultimately a view).

See also

See also URL dispatch.

route configuration

Route configuration is the act of associating request parameters with a particular route using pattern matching and route predicate statements. See URL Dispatch for more information about route configuration.

route predicate

An argument to a route configuration which implies a value that evaluates to True or False for a given request. All predicates attached to a route configuration must evaluate to True for the associated route to "match" the current request. If a route does not match the current request, the next route (in definition order) is attempted.

route prefix

A route prefix is a path prefix that is prepended to any routes that are configured while it is active. A route prefix can be set via pyramid.config.Configurator.include() or pyramid.config.Configurator.route_prefix_context().


The WSGI application created when you start a Pyramid application. The router intercepts requests, invokes traversal and/or URL dispatch, calls view functions, and returns responses to the WSGI server on behalf of your Pyramid application.


A system by Ben Bangert which parses URLs and compares them against a number of user defined mappings. The URL pattern matching syntax in Pyramid is inspired by the Routes syntax (which was inspired by Ruby On Rails pattern syntax).

routes mapper

An object which compares path information from a request to an ordered set of route patterns. See URL Dispatch.


The term used by Pyramid to define the process of importing and examining all code in a Python package or module for configuration decoration.

security policy

A security policy in Pyramid terms is an object implementing the pyramid.interfaces.ISecurityPolicy API which identifies the user associated with the current request (perhaps via a cookie or Authorization header) and determines whether or not that user is permitted to access the requested resource.


A namespace that is valid for some period of continual activity that can be used to represent a user's interaction with a web application.

session factory

A callable, which, when called with a single argument named request (a request object), returns a session object. See Using the Default Session Factory, Using Alternate Session Factories and pyramid.config.Configurator.set_session_factory() for more information.


Settings control the runtime behavior of a Pyramid application. They are the aggregation of configuration file declarations, process environment values, other additions generated by Pyramid or its add-ons and tweens, and values produced by your own code. Settings are collected at application startup. They can affect all the components which make up the the application. Pyramid itself, any tweens or Pyramid add-ons used, and your own code may reference and act on settings.


Setuptools builds on Python's distutils to provide easier building, distribution, and installation of libraries and applications.

side effect

A statement or function has a side effect when it changes a value outside its own scope. Put another way, if one can observe the change made by a function from outside that function, it has a side effect.


A singleton is a class which will only ever have one instance. As there is only one, it is shared by all other code. This makes it an example of global state.

Using a singleton is considered a poor design choice. As mutable global state, it can be changed by any other code, and so the values it represents cannot be reasoned about or tested properly.


SQLAlchemy is an object relational mapper used in tutorials within this documentation.


A list of element "left over" after the router has performed a successful traversal to a view. The subpath is a sequence of strings, e.g. ['left', 'over', 'names']. Within Pyramid applications that use URL dispatch rather than traversal, you can use *subpath in the route pattern to influence the subpath. See Using *subpath in a Route Pattern for more information.


A callable which receives an event. A callable becomes a subscriber via imperative configuration or via configuration decoration. See Using Events for more information.


A file with replaceable parts that is capable of representing some text, XML, or HTML when rendered.

thread local

A thread-local variable is one which is essentially a global variable in terms of how it is accessed and treated, however, each thread used by the application may have a different value for this same "global" variable. Pyramid uses a small number of thread local variables, as described in Thread Locals.

See also

See also the stdlib documentation for more information.

Translation Context

A string representing the "context" in which a translation was made within a given translation domain. See the gettext documentation, 11.2.5 Using contexts for solving ambiguities for more information.

Translation Directory

A translation directory is a gettext translation directory. It contains language folders, which themselves contain LC_MESSAGES folders, which contain .mo files. Each .mo file represents a set of translations for a language in a translation domain. The name of the .mo file (minus the .mo extension) is the translation domain name.

Translation Domain

A string representing the "context" in which a translation was made. For example the word "java" might be translated differently if the translation domain is "programming-languages" than would be if the translation domain was "coffee". A translation domain is represented by a collection of .mo files within one or more translation directory directories.

Translation String

An instance of pyramid.i18n.TranslationString, which is a class that behaves like a string, but has several extra attributes such as domain, msgid, and mapping for use during translation. Translation strings are usually created by hand within software, but are sometimes created on the behalf of the system for automatic template translation. For more information, see Internationalization and Localization.


A callable which receives a translation string and returns a translated string for the purposes of internationalization. A localizer supplies a translator to a Pyramid application accessible via its translate method.


The act of descending "up" a tree of resource objects from a root resource in order to find a context resource. The Pyramid router performs traversal of resource objects when a root factory is specified. See the Traversal chapter for more information. Traversal can be performed instead of URL dispatch or can be combined with URL dispatch. See Combining Traversal and URL Dispatch for more information about combining traversal and URL dispatch (advanced).

truthy string

A string represeting a value of True. Acceptable values are t, true, y, yes, on and 1.


A bit of code that sits between the Pyramid router's main request handling function and the upstream WSGI component that uses Pyramid as its 'app'. The word "tween" is a contraction of "between". A tween may be used by Pyramid framework extensions, to provide, for example, Pyramid-specific view timing support, bookkeeping code that examines exceptions before they are returned to the upstream WSGI application, or a variety of other features. Tweens behave a bit like WSGI middleware but they have the benefit of running in a context in which they have access to the Pyramid application registry as well as the Pyramid rendering machinery. See Registering Tweens.

URL dispatch

An alternative to traversal as a mechanism for locating a context resource for a view. When you use a route in your Pyramid application via a route configuration, you are using URL dispatch. See the URL Dispatch for more information.


A userid is the string representation of an identity. Just like the identity, it should identify the user associated with the current request. Oftentimes this is the ID of the user object in a database.


Venusian is a library which allows framework authors to defer decorator actions. Instead of taking actions when a function (or class) decorator is executed at import time, the action usually taken by the decorator is deferred until a separate "scan" phase. Pyramid relies on Venusian to provide a basis for its scan feature.


The Python Packaging Authority's recommended tool for creating virtual environments on Python 3.3 and greater.

Note: whenever you encounter commands prefixed with $VENV (Unix) or %VENV (Windows), know that that is the environment variable whose value is the root of the virtual environment in question.


Common vernacular for a view callable.

view callable

A "view callable" is a callable Python object which is associated with a view configuration; it returns a response object . A view callable accepts a single argument: request, which will be an instance of a request object. An alternate calling convention allows a view to be defined as a callable which accepts a pair of arguments: context and request: this calling convention is useful for traversal-based applications in which a context is always very important. A view callable is the primary mechanism by which a developer writes user interface code within Pyramid. See Views for more information about Pyramid view callables.

view configuration

View configuration is the act of associating a view callable with configuration information. This configuration information helps map a given request to a particular view callable and it can influence the response of a view callable. Pyramid views can be configured via imperative configuration, or by a special @view_config decorator coupled with a scan. See View Configuration for more information about view configuration.

view deriver

A view deriver is a composable component of the view pipeline which is used to create a view callable. A view deriver is a callable implementing the pyramid.interfaces.IViewDeriver interface. Examples of built-in derivers including view mapper, the permission checker, and applying a renderer to a dictionary returned from the view.

View handler

A view handler ties together pyramid.config.Configurator.add_route() and pyramid.config.Configurator.add_view() to make it more convenient to register a collection of views as a single class when using URL dispatch. View handlers ship as part of the pyramid_handlers add-on package.

View Lookup

The act of finding and invoking the "best" view callable, given a request and a context resource.

view mapper

A view mapper is a class which implements the pyramid.interfaces.IViewMapperFactory interface, which performs view argument and return value mapping. This is a plug point for extension builders, not normally used by "civilians".

view name

The "URL name" of a view, e.g index.html. If a view is configured without a name, its name is considered to be the empty string (which implies the default view).

view predicate

An argument to a view configuration which evaluates to True or False for a given request. All predicates attached to a view configuration must evaluate to true for the associated view to be considered as a possible callable for a given request.

virtual environment

An isolated Python environment that allows packages to be installed for use by a particular application, rather than being installed system wide.

virtual root

A resource object representing the "virtual" root of a request; this is typically the physical root object unless Virtual Hosting is in use.


The virtualenv tool that allows one to create virtual environments. In Python 3.3 and greater, venv is the preferred tool.

Note: whenever you encounter commands prefixed with $VENV (Unix) or %VENV (Windows), know that that is the environment variable whose value is the root of the virtual environment in question.


A WSGI server that runs on Unix and Windows under Python 2.7+ and Python 3.3+. Projects generated via Pyramid cookiecutters use Waitress as a WGSI server. See for detailed information.


WebOb is a WSGI request/response library created by Ian Bicking.


WebTest is a package which can help you write functional tests for your WSGI application.


Web Server Gateway Interface. This is a Python standard for connecting web applications to web servers, similar to the concept of Java Servlets. Pyramid requires that your application be served as a WSGI application.


Zope Configuration Markup Language, an XML dialect used by Zope and pyramid_zcml for configuration tasks.


Zope Object Database, a persistent Python object store.


The Z Object Publishing Framework, a full-featured Python web framework.

Zope Component Architecture

The Zope Component Architecture (aka ZCA) is a system which allows for application pluggability and complex dispatching based on objects which implement an interface. Pyramid uses the ZCA "under the hood" to perform view dispatching and other application configuration tasks.


The Zope Page Template templating language.