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68 lines
2.0 KiB
C++
68 lines
2.0 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_fallible_h
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#define mozilla_fallible_h
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#if defined(__cplusplus)
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/* Explicit fallible allocation
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*
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* Memory allocation (normally) defaults to abort in case of failed
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* allocation. That is, it never returns NULL, and crashes instead.
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*
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* Code can explicitely request for fallible memory allocation thanks
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* to the declarations below.
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*
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* The typical use of the mozilla::fallible const is with placement new,
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* like the following:
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*
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* foo = new (mozilla::fallible) Foo();
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*
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* The following forms, or derivatives, are also possible but deprecated:
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*
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* foo = new ((mozilla::fallible_t())) Foo();
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*
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* const mozilla::fallible_t fallible = mozilla::fallible_t();
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* bar = new (f) Bar();
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*
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* It is also possible to declare method overloads with fallible allocation
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* alternatives, like so:
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*
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* class Foo {
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* public:
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* void Method(void *);
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* void Method(void *, const mozilla::fallible_t&);
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* };
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*
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* Foo foo;
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* foo.Method(nullptr, mozilla::fallible);
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*
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* If that last method call is in a method that itself takes a const
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* fallible_t& argument, it is recommended to propagate that argument
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* instead of using mozilla::fallible:
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*
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* void Func(Foo &foo, const mozilla::fallible_t& aFallible) {
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* foo.Method(nullptr, aFallible);
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* }
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*
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*/
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namespace mozilla {
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struct fallible_t { };
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/* This symbol is kept unexported, such that in corner cases where the
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* compiler can't remove its use (essentially, cross compilation-unit
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* calls), the smallest machine code is used.
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* Depending how the linker packs symbols, it will consume between 1 and
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* 8 bytes of read-only data in each executable or shared library, but
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* only in those where it's actually not optimized out by the compiler.
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*/
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extern const fallible_t fallible;
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} // namespace mozilla
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#endif
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#endif // mozilla_fallible_h
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