WTF does WTF represent in the WebKit code base?

Question

I downloaded Chromium's code base and ran across the WTF namespace.

namespace WTF {
    /*
     * C++'s idea of a reinterpret_cast lacks sufficient cojones.
     */
    template<typename TO, typename FROM>
    TO bitwise_cast(FROM in)
    {
        COMPILE_ASSERT(sizeof(TO) == sizeof(FROM), WTF_wtf_reinterpret_cast_sizeof_types_is_equal);
        union {
            FROM from;
            TO to;
        } u;
        u.from = in;
        return u.to;
    }
} // namespace WTF

Does this mean what I think it means? Could be so, the bitwise_cast implementation specified here will not compile if either TO or FROM is not a POD and is not (AFAIK) more powerful than C++ built in reinterpret_cast.

The only point of light I see here is the nobody seems to be using bitwise_cast in the Chromium project.

@KennyTM please see http://meta.stackexchange.com/questions/45844/is-the-tag-wtf-acceptable for a discussion of how to tag this question — Earlz, May 31 '10 at 06:15
Wow, that class is not described by "Web Template Framework." It's just a convenient abbreviation. — macetw, Jun 06 '14 at 12:13

score 91 · Accepted Answer · edited Jan 16 '18 at 08:24

91

It’s short for Web Template Framework and provides commonly used functions all over the WebKit codebase.

edited Jan 16 '18 at 08:24

Mathias Bynens

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answered May 07 '09 at 12:00

ismail

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as in C++ templates doing common stuff :) – ismail Jan 31 '12 at 12:17
any way of cloning that library? – Victor Jan 05 '17 at 11:22
Citations please. Does it do templating like Mustache or JSP? – adib Mar 23 '17 at 08:53
@adib No, the "template" really refers to C++ templates and nothing else. See https://trac.webkit.org/wiki/SourceDirectory and https://webkit.org/blog/6161/locking-in-webkit/ (for WebKit sources) and https://chromium.googlesource.com/chromium/src/+/master/third_party/blink/renderer/platform/wtf/README.md (for Blink source). – Timothy Gu Apr 27 '20 at 20:46

score 5 · Answer 2 · edited May 23 '17 at 11:54

5

It is to avoid the strict-aliasing optimization problem:

gcc, strict-aliasing, and casting through a union

edited May 23 '17 at 11:54

Community

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answered Jun 10 '10 at 17:24

Stan

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score 2 · Answer 3 · answered May 07 '09 at 11:56

2

Could be so, the bitwise_cast implementation specified here yields undefined behaviour if either TO or FROM is not a POD

If FROM or TO are not POD types, the compilation would fail with current C++ standard because you wouldn't be able to put them in union.

answered May 07 '09 at 11:56

Artyom

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Not sure. If your class contains a pointer-to-member, it's not a POD but it still can go in a union, I think. – MSalters May 07 '09 at 13:22

WTF does WTF represent in the WebKit code base?

3 Answers3