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41 lines
1.8 KiB
Text
41 lines
1.8 KiB
Text
There are four ways to hi(shared_ptr: defining) define tt(shared_ptr)
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objects. Each definition contains the usual tt(<type>) specifier between
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angle brackets:
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itemization(
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it() The default constructor simply creates a tt(shared_ptr) object that
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does not point to a particular block of memory. Its pointer is initialized to
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0 (zero):
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verb(
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shared_ptr<type> identifier;
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)
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This form is discussed in section ref(SHAREDPLAIN).
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it() The copy constructor initializes a tt(shared_ptr) so that both
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objects share the memory pointed at by the existing object. The copy
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constructor also increments the tt(shared_ptr)'s reference count. Example:
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verb(
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shared_ptr<string> org(new string("hi there"));
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shared_ptr<string> copy(org); // reference count now 2
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)
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it() The move constructor initializes a tt(shared_ptr) with the pointer
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and reference count of a temporary tt(shared_ptr). The temporary
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tt(shared_ptr) is changed into a 0-pointer. An existing tt(shared_ptr) may
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have its data moved to a newly defined tt(shared_ptr) (turning the existing
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tt(shared_ptr) into a 0-pointer as well) by applying
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hi(move)tt(std::move). Example:
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verb(
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shared_ptr<string> grabber(shared_ptr<string>(new string("hi there")));
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)
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it() The form that is used most often initializes a tt(shared_ptr) object
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to the block of dynamically allocated memory that is passed to the object's
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constructor. Optionally ti(deleter) can be provided. A (free) function (or
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function object) receiving the tt(shared_ptr)'s pointer as its argument can be
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passed as deleter. It is supposed to return the dynamically allocated
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memory to the common pool (doing nothing if the pointer equals zero).
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verb(
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shared_ptr<type> identifier (new-expression [, deleter]);
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)
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This form is discussed in section ref(SHAREDNEW).
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)
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