Difference between revisions of "Conditional Compiler Options"

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This page collects ideas of how to implement conditional compiler options in lazarus.
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{{Conditional_Compiler_Options}}
  
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First it should be collected the cases, where conditional compiler options are needed.
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==Overview==
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Since Lazarus 0.9.29 you can define build modes and conditional compiler options. These options depend on current target OS, CPU, widgetset and project's build mode.
  
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=Case studies=
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For conditionals see here [[Macros and Conditionals]].
  
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==Conditional Package Requirement: VirtualTreeView / multilog==
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You can set the build macros for a package via [[IDE_Window: Compiler Options#Build_Macros|package editor / Compiler Options / Build Macros]].
  
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Make it possible to define a package requirement as optional (Should be
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You can set the build macros for a project via [[IDE Window: Compiler Options#Build_Macros|Project / Project Options / Compiler Options / Build Macros]].
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available both to package and program).
 
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Concrete situation: VirtualTreeView requires multilog package to help
 
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debug code. In a release it is not desired to have such dependency.  
 
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Currently there are two possibilities:
 
  
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* in the release remove the dependency from the package, and then add again to reenable debugging.
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==Target specific units - Doable via FPC directives, no Lazarus extras needed==
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* enclose the units of the package with {$IFNDEF MYRELEASE} and add -dMYRELEASE to the project and all package compiler options (or fpc.cfg).
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Concrete situation: LCL extensions package has a unit (OleUtils) that implements TOLEStream. It only makes sense in Windows. Currently the unit is added in all widgetsets but all code is wrapped around a ifdef Windows define so is seen as a dummy unit in other widgetsets.
  
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An idea is to have groups of conditional requirements. Each group would
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Notes:
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have  a define value associated to be used at compile time (e.g:
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*All units should be added to the package, independent if they are used. If a unit should not always be compiled (not added to the uses section of the package), just unset the 'uses unit' checkbox and add for example {$IFDEF win32}uses oleutils{$ENDIF} to a package unit.
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'DEBUG_CODE') and child packages. Each group would have an enabled flag.  
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*You can put units and include files specific to targets into sub directories as demonstrated in the Lazarus and FPC sources (units/$(TargetOS)).
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If group is enabled, the child packages are added as requirements and  
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*Since 0.9.31 multiple files with the same name can be added to packages.
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the define value passed with -d to the compiler.
 
  
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*Disadvantage: Other packages will use the same Debug/Release differences. In big projects normally only a small part should be set verbose (into debugging mode).
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+=What will not be implemented==
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*A global Debug/Verbose buildmode. Almost no one wants to increase verbosity of all packages, nor debug all packages. But you can define one for your own packages.
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*Conditional units. This is already flexible doable via FPC directives and IDE macros.
  
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==Target specific units==
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==Future development / Wishes==
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*Use a package only under one target, e.g. only under Windows and OS X, but not under Linux or BSD.
  
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Make units packages/projects optional according to widgetset.
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{{Template:Directives, Defines and Conditionals}}
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Concrete situation: LCL extensions package has a unit (OleUtils) that
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[[Category:Conditionals]]
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implements TOLEStream. It only makes sense in win32. Currently the unit
 
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is added in all widgetsets but all code is wrapped around a ifdef
 
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Windows define so is seen as a dummy unit in other widgetsets.
 
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Notes:
 
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*All units should be added to the package, independent if they are used. If a unit should not always be compiled in (not added to the uses section of the package), just unset the 'uses unit' checkbox.
 
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*If the "uses unit" flag is not set, the unit will not be compiled. Nor in win32 (where is needed) neither in the other systems. It will be compiled '''only''' if another unit in the package uses it. So you must add for example {$IFDEF win32}uses oleutils.pas{$ENDIF} somewhere to one of the package units.
 
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*The above example is about windows. That has nothing to do with the widgetset. The qt and gtk2 widgetsets are also running under windows.
 
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*You can put units specific to targets into sub directories as demonstrated in the Lazarus and FPC sources (units/$(TargetOS)).
 
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*Conclusion: There is no real need for conditional options for single units, as this is already possible.
 

Latest revision as of 16:27, 25 March 2017

│ English (en) │ français (fr) │

Overview

Since Lazarus 0.9.29 you can define build modes and conditional compiler options. These options depend on current target OS, CPU, widgetset and project's build mode.

For conditionals see here Macros and Conditionals.

You can set the build macros for a package via package editor / Compiler Options / Build Macros.

You can set the build macros for a project via Project / Project Options / Compiler Options / Build Macros.

Target specific units - Doable via FPC directives, no Lazarus extras needed

Concrete situation: LCL extensions package has a unit (OleUtils) that implements TOLEStream. It only makes sense in Windows. Currently the unit is added in all widgetsets but all code is wrapped around a ifdef Windows define so is seen as a dummy unit in other widgetsets.

Notes:

  • All units should be added to the package, independent if they are used. If a unit should not always be compiled (not added to the uses section of the package), just unset the 'uses unit' checkbox and add for example {$IFDEF win32}uses oleutils{$ENDIF} to a package unit.
  • You can put units and include files specific to targets into sub directories as demonstrated in the Lazarus and FPC sources (units/$(TargetOS)).
  • Since 0.9.31 multiple files with the same name can be added to packages.

+=What will not be implemented==

  • A global Debug/Verbose buildmode. Almost no one wants to increase verbosity of all packages, nor debug all packages. But you can define one for your own packages.
  • Conditional units. This is already flexible doable via FPC directives and IDE macros.

Future development / Wishes

  • Use a package only under one target, e.g. only under Windows and OS X, but not under Linux or BSD.
Directives, definitions and conditionals definitions
global compiler directives • local compiler directives

Conditional Compiler Options • Conditional compilation • Macros and Conditionals • Platform defines
$IF


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