53 lines
1.5 KiB
Plaintext
53 lines
1.5 KiB
Plaintext
== Why is this an issue?
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C provides a way of defining or aliasing a type through ``++typedef++``. On top of it, {cpp} adds ``++using++`` that can do the same and more.
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Using a macro to define a type is inferior to the previous ways for two reasons:
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* macros cannot be enclosed into scopes. Or at least, doing so is cumbersome and error-prone, as in that case, the macro needs to be defined and undefined manually.
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* macros are handled by the preprocessor and are not understood by the compiler. They can easily pollute the code in places where types are not expected. ``++typedef++`` and ``++using++`` are known to the compiler to define types and can be more strictly checked.
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As a result, macros should not be used as a replacement for ``++typedef++`` or ``++using++``.
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=== Noncompliant code example
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[source,cpp]
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----
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#define UINT unsigned int // Noncompliant
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#define INT int // Noncompliant
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UINT uabs( INT i );
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----
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=== Compliant solution
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[source,cpp]
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----
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typedef unsigned int UINT;
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typedef int INT;
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UINT uabs( INT i );
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----
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or
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[source,cpp]
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----
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using UINT = unsigned int;
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using INT = int;
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UINT uabs( INT i );
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----
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== Resources
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=== Documentation
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* {cpp} reference - https://en.cppreference.com/w/cpp/language/typedef[typedef specifier]
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* {cpp} reference - https://en.cppreference.com/w/cpp/language/type_alias[Type alias, alias template]
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=== Standards
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* CERT - https://wiki.sei.cmu.edu/confluence/display/c/PRE03-C.+Prefer+typedefs+to+defines+for+encoding+non-pointer+types[PRE03-C. Prefer typedefs to defines for encoding non-pointer types]
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