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Jsctypes/api: Difference between revisions
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→Conversions: Add note about not autoconverting from a char.array(10) to a JS string
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* Otherwise ''x'' is of an array, struct, or pointer type. If the argument ''x'' is already a <code>CData</code> object, return it. Otherwise allocate a buffer containing a copy of the C/C++ value ''x'', and return a <code>CData</code> object of the appropriate type referring to the object in the new buffer. | * Otherwise ''x'' is of an array, struct, or pointer type. If the argument ''x'' is already a <code>CData</code> object, return it. Otherwise allocate a buffer containing a copy of the C/C++ value ''x'', and return a <code>CData</code> object of the appropriate type referring to the object in the new buffer. | ||
Note that | Note that null C/C++ pointers do not convert to the JavaScript <code>null</code> value. ''(Open issue: Should we? Is there any value in retaining the type of a particular null pointer?)'' | ||
''(Arrays of characters do not convert to JavaScript strings. Rationale: Suppose <code>x</code> is a <code>CData</code> object of a struct type with a member <code>a</code> of type <code>char[10]</code>. Then <code>x.a[0] = '\0';</code> should modify the contents of the array. This implies that <code>x.a</code> must be a <code>CData</code> object, not a JavaScript string.)'' | |||
<code>'''ImplicitConvert(''val'', ''t'')'''</code> - Convert the JavaScript value ''val'' to a C/C++ value of type ''t''. This is called whenever a JavaScript value of any kind is passed to a parameter of a ctypes-declared function, passed to <code>''cdata''.value = ''val''</code>, or assigned to an array element or struct member, as in <code>''carray''[''i''] = ''val''</code> or <code>''cstruct''.''member'' = ''val''</code>. This function is intended to lose precision only when there is no reasonable alternative. It generally does not coerce values of one type to another type. | <code>'''ImplicitConvert(''val'', ''t'')'''</code> - Convert the JavaScript value ''val'' to a C/C++ value of type ''t''. This is called whenever a JavaScript value of any kind is passed to a parameter of a ctypes-declared function, passed to <code>''cdata''.value = ''val''</code>, or assigned to an array element or struct member, as in <code>''carray''[''i''] = ''val''</code> or <code>''cstruct''.''member'' = ''val''</code>. This function is intended to lose precision only when there is no reasonable alternative. It generally does not coerce values of one type to another type. | ||