Replace word causes buffer issue

Question

I wannt to replace a specific word in multiple files. First time i do "C-c c" everything works fine, but when i repeat the command the text is not updated in the newly created files correctly. The files contain same content as the first pair of files(.cpp, .h). I think it is a buffer issue in replace-word-in-string but i dont know how to fix it? I'm a beginner at Elisp please explain in simple terms, thanks for helping me out.

;;Prototype source
(setq sourceCode "//Include Librarys
#include MyClass

//Include Files


//******
//MyClass::MyClass
//******
MyClass::MyClass() {}

//******
//MyClass::~MyClass
//******
MyClass::~MyClass() {}

")

;;Prototype Header
(setq headerCode "#ifndef MYCLASS
#define MYCLASS

//Include Librarys

//Include Files


//Forward declarations


class MyClass {
public:
 MyClass();
 ~MyClass();

private:

};

#endif //!MyClass
")

;;Create CLASS
(global-set-key (kbd "C-c c")
   (defun create-class (directory name)
    (interactive "s(Create a new class) Enter path: 
    sEnter class name: ")

    (setq directory "c:/Programming/") ;only for degugging
    (setq path (concat directory name))
    (setq pathSource (concat path ".cpp"))
    (setq pathHeader (concat path ".h"))

    ;Replace default class name with user specified class name
    (setq sourceCode (replace-word-in-string sourceCode name "MyClass"))

    (setq headerCode (replace-word-in-string headerCode name "MyClass"))

    ;Check if file exist in current directory
    (if (and (file-exists-p pathSource)(file-exists-p pathHeader))
      (message "%s" "Filename already exist, no files where created!")
      (write-region sourceCode nil pathSource) ;Write to files.
      (write-region headerCode nil pathHeader)
      (message "Created source file: %s and created header file: %s" pathSource pathHeader)
    )
  )
) 

(defun replace-word-in-string(string replacementWord searchedWord)
    (with-temp-buffer
      (insert string)
      (goto-char (point-min))
      (while (re-search-forward searchedWord nil t)
        (replace-match replacementWord nil t)
      (setq retString (buffer-string)) ;returns all content in buffer as a   string
      )
   )
retString
)

Answer 1

I patched up your code so that it works. You'll have to study the differences to see what the problems were. Good luck!

(setq sourceCode "//Include Librarys
#include MyClass
//******
//MyClass::MyClass
//******
MyClass::MyClass() {}
")

File Created:
//Include Librarys
#include HiThere
//******
//HiThere::HiThere
//******
HiThere::HiThere() {}


;;Prototype Header
(setq headerCode "#ifndef MYCLASS
#define MYCLASS
class MyClass {
public:
 MyClass();
 ~MyClass();
};
#endif //!MyClass
")

File Created:
#ifndef MYCLASS
#define MYCLASS
class HiThere {
public:
 HiThere();
 ~HiThere();
};
#endif //!HiThere


(defun create-class (directory name)
  "Create a new class and header file."
  (interactive "s(Create a new class) Enter path:
    sEnter class name: ")

  (let (path pathSource pathHeader)
    ;;(setq directory "c:/Programming/") ;only for degugging
    (setq path (concat directory name))
    (setq pathSource (concat path ".cpp"))
    (setq pathHeader (concat path ".h"))

    ;;Replace default class name with user specified class name
    (setq sourceCode (replace-word-in-string sourceCode name "MyClass"))
    (setq headerCode (replace-word-in-string headerCode name "MyClass"))

    ;;Check if file exist in current directory
    (if (and (file-exists-p pathSource)
             (file-exists-p pathHeader))
        (message "%s" "Filename already exist, no files where created!")
      ;; else no files exist, create the new ones
      (progn
        (with-temp-file pathSource
          (insert sourceCode))
        (with-temp-file pathHeader
          (insert headerCode))
        (message "Created source file: %s\nCreated header file: %s"
                 pathSource pathHeader)
        ))
    ))
;; default-directory is a variable for the current buffer directory
;; test-begin 
(create-class default-directory "HiThere")
"Created source file: /Users/me/Dropbox/../HiThere.cpp
Created header file: /Users/me/Dropbox/.../HiThere.h"
;; test-end

(defun replace-word-in-string(string replacementWord searchedWord)
  (let (retString)
    (with-temp-buffer
      (insert string)
      (goto-char (point-min))
      (while (re-search-forward searchedWord nil t)
        (replace-match replacementWord nil t))
      (setq retString (buffer-string)) ;returns all content in buffer as a string
      )
    retString))
;; test-begin
(replace-word-in-string "How are you?" "busy" "are")
"How busy you?"
;; test-end

Update 1

The problem you are having is that you are using external "free" variables to drag in the template source file, and then resetting those variables to the replaced strings the first time through.

The second time through, the template files have changed, so they no longer contain the "MyClass" searched-for word. So no string replacements occur.

In the code below, I have used two local variables newSource and newHeader to hold the replaced code. This solves the problem of resetting your free variables.

(let (path pathSource pathHeader newSource newHeader)

;;Replace default class name with user specified class name
(setq newSource (replace-word-in-string sourceCode name "MyClass"))
(setq newHeader (replace-word-in-string headerCode name "MyClass"))

    (message "%s" "Filename already exist, no files where created!")
  ;; else no files exist, create the new ones
  (progn
    (with-temp-file pathSource
      (insert newSource))
    (with-temp-file pathHeader
      (insert newHeader))
    (message "Created source file: %s\nCreated header file: %s"
             pathSource pathHeader)
    ))

Answer 2

Here is a working copy of the code(everything is included copy/paste into Emacs and run it), for an explenation of the answere see Kevin posts.

(defun create-class (directory name)
"Create a new class(source and  header file."
(interactive "s(Create a new class) Enter path:
sEnter class name: ")

  (let (path newSourceCode newHeaderCode pathSource pathHeader)
    (setq directory (concat directory "/"))
    (setq path (concat directory name))
    (setq pathSource (concat path ".cpp"))
    (setq pathHeader (concat path ".h"))

    ;;Replace default class name with user specified class name
    (setq newSourceCode (replace-word-in-string sourceCode name "MyClass"))
    (setq newHeaderCode (replace-word-in-string headerCode name "MyClass"))

    ;;Check if file exist in current directory
    (if (and (file-exists-p pathSource)
         (file-exists-p pathHeader))
    (message "%s" "Filename already exist, no files where created!")
   ;; else no files exist, create the new ones
   (progn
    (with-temp-file pathSource
      (insert newSourceCode))
    (with-temp-file pathHeader
      (insert newHeaderCode))
    (message "Created source file: %s\nCreated header file: %s"
             pathSource pathHeader)
    ))
))

(defun replace-word-in-string(string replacementWord searchedWord)
  (let (retString)
    (with-temp-buffer
      (insert string)
      (goto-char (point-min))
      (while (re-search-forward searchedWord nil t)
        (replace-match replacementWord nil t))
      (setq retString (buffer-string)) ;returns all content in buffer as a   string
      )
 retString))

(setq sourceCode "//Include Librarys
#include MyClass.h

//Include Files


//******
//MyClass::MyClass
//******
MyClass::MyClass() {}

//******
//MyClass::~MyClass
//******
MyClass::~MyClass() {}

")

;;Prototype Header
(setq headerCode "#ifndef MYCLASS_H
#define MYCLASS_H

//Include Librarys

//Include Files


//Forward declarations


class MyClass {
public:
  MyClass();
  ~MyClass();

private:

};

#endif //!MYCLASS_H
")

;;Create CLASS
(global-set-key (kbd "C-c c")
  'create-class
)