diff --git a/changelog/778.doc.rst b/changelog/778.doc.rst new file mode 100644 index 00000000..ee4e285c --- /dev/null +++ b/changelog/778.doc.rst @@ -0,0 +1 @@ +Illustrate the entry and resumption order of nested new-style hook wrappers. diff --git a/docs/_static/img/wrapper-order.png b/docs/_static/img/wrapper-order.png new file mode 100644 index 00000000..c3082d64 Binary files /dev/null and b/docs/_static/img/wrapper-order.png differ diff --git a/docs/_static/img/wrapper-order.svg b/docs/_static/img/wrapper-order.svg new file mode 100644 index 00000000..8813ac16 --- /dev/null +++ b/docs/_static/img/wrapper-order.svg @@ -0,0 +1,98 @@ + +Embedded inter font subsets retain the following copyright and SIL OFL 1.1 license. The surrounding diagram retains its repository license. + +Copyright 2016 The Inter Project Authors (https://github.com/rsms/inter) Inter-Italic[opsz,wght].ttf: Copyright 2016 The Inter Project Authors (https://github.com/rsms/inter) + +This Font Software is licensed under the SIL Open Font License, Version 1.1. +This license is copied below, and is also available with a FAQ at: +http://scripts.sil.org/OFL + + +----------------------------------------------------------- +SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007 +----------------------------------------------------------- + +PREAMBLE +The goals of the Open Font License (OFL) are to stimulate worldwide +development of collaborative font projects, to support the font creation +efforts of academic and linguistic communities, and to provide a free and +open framework in which fonts may be shared and improved in partnership +with others. + +The OFL allows the licensed fonts to be used, studied, modified and +redistributed freely as long as they are not sold by themselves. The +fonts, including any derivative works, can be bundled, embedded, +redistributed and/or sold with any software provided that any reserved +names are not used by derivative works. The fonts and derivatives, +however, cannot be released under any other type of license. The +requirement for fonts to remain under this license does not apply +to any document created using the fonts or their derivatives. + +DEFINITIONS +"Font Software" refers to the set of files released by the Copyright +Holder(s) under this license and clearly marked as such. This may +include source files, build scripts and documentation. + +"Reserved Font Name" refers to any names specified as such after the +copyright statement(s). + +"Original Version" refers to the collection of Font Software components as +distributed by the Copyright Holder(s). + +"Modified Version" refers to any derivative made by adding to, deleting, +or substituting -- in part or in whole -- any of the components of the +Original Version, by changing formats or by porting the Font Software to a +new environment. + +"Author" refers to any designer, engineer, programmer, technical +writer or other person who contributed to the Font Software. + +PERMISSION & CONDITIONS +Permission is hereby granted, free of charge, to any person obtaining +a copy of the Font Software, to use, study, copy, merge, embed, modify, +redistribute, and sell modified and unmodified copies of the Font +Software, subject to the following conditions: + +1) Neither the Font Software nor any of its individual components, +in Original or Modified Versions, may be sold by itself. + +2) Original or Modified Versions of the Font Software may be bundled, +redistributed and/or sold with any software, provided that each copy +contains the above copyright notice and this license. These can be +included either as stand-alone text files, human-readable headers or +in the appropriate machine-readable metadata fields within text or +binary files as long as those fields can be easily viewed by the user. + +3) No Modified Version of the Font Software may use the Reserved Font +Name(s) unless explicit written permission is granted by the corresponding +Copyright Holder. This restriction only applies to the primary font name as +presented to the users. + +4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font +Software shall not be used to promote, endorse or advertise any +Modified Version, except to acknowledge the contribution(s) of the +Copyright Holder(s) and the Author(s) or with their explicit written +permission. + +5) The Font Software, modified or unmodified, in part or in whole, +must be distributed entirely under this license, and must not be +distributed under any other license. The requirement for fonts to +remain under this license does not apply to any document created +using the Font Software. + +TERMINATION +This license becomes null and void if any of the above conditions are +not met. + +DISCLAIMER +THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF +MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT +OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE +COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, +INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL +DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM +OTHER DEALINGS IN THE FONT SOFTWARE. + +Pluggy nested hook wrapper execution orderOuter and inner wrappers suspend at yield before non-wrapper implementations run. The result returns through the inner wrapper and then the outer wrapper.Suspend at yieldSuspend at yieldSend result to yieldSend wrapper return valueOuter wrapperFirst entered, lastresumedInner wrapperLast entered, firstresumedHookimplementationsNon-wrapper calls diff --git a/docs/index.rst b/docs/index.rst index e3e2afdf..41949695 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -435,6 +435,28 @@ The function should do one of two things: The return value or exception propagate to further hook wrappers, and finally to the hook caller. +With multiple wrappers, execution enters from the outside in and resumes +from the inside out. In this successful-call example, the outer wrapper reaches +its ``yield`` first, then the inner wrapper reaches its ``yield``, and then the +non-wrapper implementations run. Pluggy sends their result to the inner +wrapper's ``yield``; that wrapper's return value is sent to the outer wrapper's +``yield``. The outer wrapper's return value becomes the hook call's result. + +.. figure:: _static/img/wrapper-order.png + :alt: Outer and inner wrappers suspend at yield before the non-wrapper implementations run; the result returns through the inner wrapper and then the outer wrapper. + :width: 690px + + Successful hook call with two new-style wrappers. + :download:`Editable SVG <_static/img/wrapper-order.svg>`. + Diagram created with `svgdiagram.ai `_. + +The arrows show execution order managed by Pluggy, rather than direct calls +between wrapper functions. ``tryfirst`` and ``trylast`` affect wrapper entry +order as described in :ref:`callorder`; wrappers resume in reverse entry order. +If an inner call raises, Pluggy throws the exception into the suspended +wrapper instead of sending a result. Each wrapper can preserve or replace the +result or exception before the next outer wrapper resumes. + Also see the :ref:`pytest:hookwrapper` section in the ``pytest`` docs. .. _old_style_hookwrappers: