[Cmake-commits] CMake branch, next, updated. v2.8.12.1-6774-g1de8a23
Stephen Kelly
steveire at gmail.com
Mon Jan 6 13:19:10 EST 2014
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http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=1de8a23819ea56849f3567e3a637f8f0a4186ab7
commit 1de8a23819ea56849f3567e3a637f8f0a4186ab7
Merge: 3b4d3e4 58c174e
Author: Stephen Kelly <steveire at gmail.com>
AuthorDate: Mon Jan 6 13:19:09 2014 -0500
Commit: CMake Topic Stage <kwrobot at kitware.com>
CommitDate: Mon Jan 6 13:19:09 2014 -0500
Merge topic 'doc-cpp-allowed' into next
58c174e Help: Document the C++ subset permitted for CMake code.
http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=58c174e945cc46f34ef862cc35ee013a536a5c69
commit 58c174e945cc46f34ef862cc35ee013a536a5c69
Author: Stephen Kelly <steveire at gmail.com>
AuthorDate: Sat Jan 4 22:07:14 2014 +0100
Commit: Stephen Kelly <steveire at gmail.com>
CommitDate: Mon Jan 6 19:15:31 2014 +0100
Help: Document the C++ subset permitted for CMake code.
This may be incomplete, but further limitations can be added when
needed.
diff --git a/Help/manual/cmake-developer.7.rst b/Help/manual/cmake-developer.7.rst
index 5857acf..d5fbc98 100644
--- a/Help/manual/cmake-developer.7.rst
+++ b/Help/manual/cmake-developer.7.rst
@@ -13,6 +13,165 @@ Introduction
This manual is intended for reference by developers modifying the CMake
source tree itself.
+
+Permitted C++ Subset
+====================
+
+CMake is required to build with ancient C++ compilers and standard library
+implementations. Some common C++ constructs may not be used in CMake in order
+to build with such toolchains.
+
+std::vector::at
+---------------
+
+The ``at()`` member function of ``std::vector`` may not be used. Use
+``operator[]`` instead:
+
+.. code-block:: c++
+
+ std::vector<int> someVec = getVec();
+ int i1 = someVec.at(5); // Wrong
+ int i2 = someVec[5]; // Ok
+
+std::string::append
+-------------------
+
+The ``append()`` member function of ``std::string`` may not be used. Use
+``operator+=`` instead:
+
+.. code-block:: c++
+
+ std::string stringBuilder;
+ stringBuilder.append("chunk"); // Wrong
+ stringBuilder += "chunk"; // Ok
+
+std::set const iterators
+------------------------
+
+The ``find()`` member function of a ``const`` ``std::set`` instance may not be
+used in a comparison with the iterator returned by ``end()``:
+
+.. code-block:: c++
+
+ const std::set<cmStdString>& someSet = getSet();
+ if (someSet.find("needle") == someSet.end()) // Wrong
+ {
+ // ...
+ }
+
+The return value of ``find()`` must be assigned to an intermediate
+``const_iterator`` for comparison:
+
+.. code-block:: c++
+
+ const std::set<cmStdString>& someSet;
+ const std::set<cmStdString>::const_iterator i = someSet.find("needle");
+ if (i != propSet.end()) // Ok
+ {
+ // ...
+ }
+
+Char Array to ``string`` Conversions with Algorithms
+----------------------------------------------------
+
+In some implementations, algorithms operating on iterators to a container of
+``std::string`` can not accept a ``const char*`` value:
+
+.. code-block:: c++
+
+ const char* dir = /*...*/;
+ std::vector<std::string> vec;
+ // ...
+ std::binary_find(vec.begin(), vec.end(), dir); // Wrong
+
+The ``std::string`` may need to be explicitly constructed:
+
+.. code-block:: c++
+
+ const char* dir = /*...*/;
+ std::vector<std::string> vec;
+ // ...
+ std::binary_find(vec.begin(), vec.end(), std::string(dir)); // Ok
+
+std::auto_ptr
+-------------
+
+Some implementations have a ``std::auto_ptr`` which can not be used as a
+return value from a function. ``std::auto_ptr`` may not be used. Use
+``cmsys::auto_ptr`` instead.
+
+std::vector::insert and std::set
+--------------------------------
+
+Use of ``std::vector::insert`` with an iterator whose ``element_type`` requires
+conversion is not allowed:
+
+.. code-block:: c++
+
+ std::set<cmStdString> theSet;
+ std::vector<std::string> theVector;
+ theVector.insert(theVector.end(), theSet.begin(), theSet.end()); // Wrong
+
+A loop must be used instead:
+
+.. code-block:: c++
+
+ std::set<cmStdString> theSet;
+ std::vector<std::string> theVector;
+ for(std::set<cmStdString>::iterator li = theSet.begin();
+ li != theSet.end(); ++li)
+ {
+ theVector.push_back(*li);
+ }
+
+Template Parameter Defaults
+---------------------------
+
+On ancient compilers, C++ template must use template parameters in function
+arguments. If no parameter of that type is needed, the common workaround is
+to add a defaulted pointer to the type to the templated function. However,
+this does not work with other ancient compilers:
+
+.. code-block:: c++
+
+ template<typename PropertyType>
+ PropertyType getTypedProperty(cmTarget* tgt, const char* prop,
+ PropertyType* = 0) // Wrong
+ {
+
+ }
+
+.. code-block:: c++
+
+ template<typename PropertyType>
+ PropertyType getTypedProperty(cmTarget* tgt, const char* prop,
+ PropertyType*) // Ok
+ {
+
+ }
+
+and invoke it with the value ``0`` explicitly in all cases.
+
+std::min and std::max
+---------------------
+
+``min`` and ``max`` are defined as macros on some systems. ``std::min`` and
+``std::max`` may not be used. Use ``cmMinimum`` and ``cmMaximum`` instead.
+
+size_t
+------
+
+Various implementations have differing implementation of ``size_t``. When
+assigning the result of ``.size()`` on a container for example, the result
+should not be assigned to an ``unsigned int`` or similar. ``std::size_t`` must
+not be used.
+
+Templates
+---------
+
+Some template code is permitted, but with some limitations. Member templates
+may not be used, and template friends may not be used.
+
Help
====
-----------------------------------------------------------------------
Summary of changes:
Help/manual/cmake-developer.7.rst | 159 +++++++++++++++++++++++++++++++++++++
1 files changed, 159 insertions(+), 0 deletions(-)
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