Setting CString in a Struct

[HezkoreParticipant]

I have a structure with a CString field (which is defined in some external C code)
It looks something like this:

Monkey

Extern Struct ModuleDef Field m_name:CString End

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Extern Struct ModuleDef Field m_name:CString End

And I need to set the m_name field to something at start.
But since it’s a CString it means that it’s a constant and can’t be changed once initialized.
So simply doing:

Monkey

Local m := New ModuleDef m.m_name = "hello"

1 2	Local m := New ModuleDef m.m_name = "hello"

Will results in an error Value 'm.m_name' is not assignable
So how would I go about changing that field?

I’ve tried cheating and renaming the field to m_name:String but I get the error error C2440: '=': cannot convert from 'bbString' to 'const char *' since the external source wants a CString.
Same error if I do m_name:String Ptr
If I make the field a CString Ptr and pass it a Varptr to a CString variable that holds the name I get Value 'name' is not a valid variable reference

Example:

Monkey

Function Main() Local t := New Test t.str = "blah" End Struct Test Field str:CString End

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Function Main() Local t := New Test t.str = "blah" End   Struct Test Field str:CString End

[abakoboParticipant]

CString is a convenience type to be used for external funcs/methods arguments. It will convert your string to a valid external CString automaticaly while passing it!

If you really need to manipulate a CString inside Monkey2, you can do it with libc.char_t Ptr, and String.ToCString or String.FromCString. But you’ll be playing with a pure C style Ptr and can crash your app if you are not managing your memory correctly.

[abakoboParticipant]

Here is a running example with c++ code included. I’m not using any const stuff here, which could bring (a lot of?) trouble.

!!! the C++ code is awful and WILL leak. Do not use it for serious work.

It shows the use of CString thru the C++ constructor and also a direct modification of the char* field

.monkey2

Monkey

#Import "<std>" #Import "<libc>" #Import "CStringStruct.h" #Import "CStringStruct.cpp" Using std.. Using libc.. Extern Struct Somestruct Field someName:char_t Ptr Method New(name:CString) Method New() Method Destroy() Extension="delete" Method SetName(name:CString) Method GetName:char_t Ptr() End Public Function Main() Print "monkey2 extern test" Print "" Local stru:Somestruct stru=New Somestruct ("John") Print String.FromCString(stru.GetName()) Print String.FromCString(stru.someName) Local newName:="Chuck" Local mydata:=New DataBuffer( newName.CStringLength+1 ) newName.ToCString( mydata.Data,mydata.Length ) stru.someName=Cast <char_t Ptr> (mydata.Data) 'leaking memory here too Print String.FromCString(stru.GetName()) End

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#Import "<std>" #Import "<libc>"   #Import "CStringStruct.h" #Import "CStringStruct.cpp"   Using std.. Using libc..   Extern   Struct Somestruct Field someName:char_t Ptr Method New(name:CString) Method New() Method Destroy() Extension="delete" Method SetName(name:CString) Method GetName:char_t Ptr() End   Public     Function Main()   Print "monkey2 extern test" Print "" Local stru:Somestruct stru=New Somestruct ("John") Print String.FromCString(stru.GetName()) Print String.FromCString(stru.someName) Local newName:="Chuck" Local mydata:=New DataBuffer( newName.CStringLength+1 ) newName.ToCString( mydata.Data,mydata.Length ) stru.someName=Cast <char_t Ptr> (mydata.Data) 'leaking memory here too Print String.FromCString(stru.GetName()) End

.h

C++

#ifndef CSTRINGSTRUCT_H #define CSTRINGSTRUCT_H struct Somestruct { public: char* someName; Somestruct(char* name); Somestruct(); ~Somestruct(); // destructor void SetName(char* name); char* GetName(); }; #endif

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#ifndef CSTRINGSTRUCT_H #define CSTRINGSTRUCT_H struct Somestruct { public:       char* someName;     Somestruct(char* name); Somestruct();       ~Somestruct(); // destructor     void SetName(char* name); char* GetName();   };     #endif

.cpp

C++

#include "CStringStruct.h" #include <iostream> // constructor Somestruct::Somestruct(char* name) { SetName(name); } Somestruct::Somestruct() { char* name="unnamed"; SetName(name); } Somestruct::~Somestruct() { // clean your memory } // member function void Somestruct::SetName(char* name) { someName = new char[ sizeof(name) + 1 ] ; strcpy( someName, name ) ; } char* Somestruct::GetName() { return this->someName; }

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#include "CStringStruct.h" #include <iostream>   //  constructor Somestruct::Somestruct(char* name) {     SetName(name); } Somestruct::Somestruct() { char* name="unnamed"; SetName(name); }   Somestruct::~Somestruct() { // clean your memory } // member function void Somestruct::SetName(char* name) { someName = new char[ sizeof(name) + 1 ] ;     strcpy( someName, name ) ; }   char* Somestruct::GetName() {     return this->someName; }

Attachments:

1. CStringStruct.monkey2
2. CStringStruct.h

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