[英]How can I find out if a Tcl_Obj is a certain kind of ttk:: entity, such as ttk:entry?
[英]How to eval a Tcl expression that should take a Tcl_Obj in C++
在C ++代碼中,我有一個(生成的Tcl_Obj*
) Tcl_Obj*
和一個表示簡單Tcl表達式的字符串,例如: return [[obj get_a] + [obj get_b]]
。 這看起來很愚蠢,但是我是Tcl的新手,我無法理解如何將這兩個內容結合在一起調用Tcl解釋器,以使用Tcl_Obj*
對我的表達式求值:
double eval(Tcl_Interp *interp, Tcl_Obj *obj, const char * cmd)
{
//substiture obj in cmd and call the interpreter?
return Tcl_GetResult(interp); //with proper checks and so on...
}
我是否錯過了執行此操作的正確命令? 非常感謝!
您在某個地方有一個Tcl_Obj *
,您想將其作為一個表達式求值並得到double
結果? 使用Tcl_ExprDoubleObj
。
Tcl_Obj *theExpressionObj = ...; // OK, maybe an argument...
double resultValue;
int resultCode;
// Need to increase the reference count of a Tcl_Obj when you evaluate it
// whether as a Tcl script or a Tcl expression
Tcl_IncrRefCount(theExpressionObj);
resultCode = Tcl_ExprLongObj(interp, theExpressionObj, &resultValue);
// Drop the reference; _may_ deallocate or might not, but you shouldn't
// have to care (but don't use theExpressionObj after this, OK?)
Tcl_DecrRefCount(theExpressionObj);
// Need to check for an error here
if (resultCode != TCL_OK) {
// Oh no!
cerr << "Oh no! " << Tcl_GetResult(interp) << endl;
// You need to handle what happens when stuff goes wrong;
// resultValue will *not* have been written do at this point
} else {
// resultValue has what you want now
return resultValue;
}
Tcl是一個完全C的庫,因此沒有RAII包裝器,但是使用一個(可能與智能指針結合)為您管理Tcl_Obj *
引用是很有意義的。
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