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Subject: Re: [boost] [TypeIndex] Peer review period for library acceptance begins, ending Thurs 21st Nov
From: Antony Polukhin (antoshkka_at_[hidden])
Date: 2013-11-13 02:46:18

2013/11/13 Gavin Lambert <gavinl_at_[hidden]>

> On 13/11/2013 08:34, Quoth Niall Douglas:
> Boost community feedback is requested for the formal peer review of
>> the TypeIndex library by Antony Polukhin.
> [...]
> NOTE: Please read the TypeIndex documentation (linked to below)
>> before asking any questions e.g. about potential code bloat etc.
>> You'll probably find the answer already there.
> The docs for .name_demangled() indicate "Readable names may also differ
> between compilers: struct user_defined_type, user_defined_type."
> Is it feasible to enforce some sort of compiler-independent uniformity on
> this (eg. guaranteeing that even if the native typeid output would insert
> "struct" or "class", name_demangled() would strip it off before returning
> it)? It would be good for code portability if users didn't have to worry
> about possibly externally stripping such things to produce "nice" output,
> or consistent output between compilers.

This is almost impossible: different compilers decorate names differently.
This means that for each compiler we need to write parser/lexer that:
* puts const, volatile, rvalue, reference at correct position (always after
the type or always before)
* strips away class, struct, __cdecl*
* unifies template parameters representation
* makes other unifications (array representations, wchar_t and __wchar_t
unifications and so on...)

This may be done some day and `name_portable()` method can be added. But
I'm afraid this won't happen soon.

I'm also not sure "name_demangled" is a good method name, as "name" being
> mangled is a GCC implementation detail that is not true in MSVC, for
> example. I would prefer something more generic, such as "long_name" or
> "friendly_name", or like MSVC using "raw_name" in place of the current
> "name", and "name" in place of the current "name_demangled".

According to C++03 and C++11 Standard type_info::name() must return const
char*. Getting readable name requires some work and an internal buffer
inside boost::type_info. This looks like a bad solution (so "raw_name()"
and "name()" won't fit).

MSVC also mangles names, but hides that from user. So as for me,
name_demangled() looks not bad.

Best regards,
Antony Polukhin

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