[easytag] Use g_return_val_if_fail() for more invariants

[David King <davidk src gnome org>]

commit 7d64bff0492987d91339683397ebf107a1600155
Author: David King <amigadave amigadave com>
Date:   Thu May 16 23:07:57 2013 +0100

    Use g_return_val_if_fail() for more invariants

 src/browser.c |    3 +--
 src/cddb.c    |   10 ++++------
 src/et_core.c |   23 ++++++++---------------
 3 files changed, 13 insertions(+), 23 deletions(-)
---
diff --git a/src/browser.c b/src/browser.c
index 5244f0d..361c4b8 100644
--- a/src/browser.c
+++ b/src/browser.c
@@ -623,8 +623,7 @@ gboolean Browser_List_Key_Press (GtkWidget *list, GdkEvent *event, gpointer data
 static gboolean
 Browser_List_Button_Press (GtkTreeView *treeView, GdkEventButton *event)
 {
-    if (!event)
-        return FALSE;
+    g_return_val_if_fail (event != NULL, FALSE);
 
     if (event->type==GDK_2BUTTON_PRESS && event->button==1)
     {
diff --git a/src/cddb.c b/src/cddb.c
index a568b99..2564b4d 100644
--- a/src/cddb.c
+++ b/src/cddb.c
@@ -1424,8 +1424,7 @@ Cddb_Track_List_Invert_Selection ()
 static gboolean
 Cddb_Track_List_Button_Press (GtkTreeView *treeView, GdkEventButton *event)
 {
-    if (!event)
-        return FALSE;
+    g_return_val_if_fail (event != NULL, FALSE);
 
     if (event->type==GDK_2BUTTON_PRESS && event->button==1)
     {
@@ -3285,8 +3284,7 @@ Cddb_Get_Album_Tracks_List (GtkTreeSelection* selection)
     gboolean   read_track_offset = FALSE;
     GtkTreeIter row;
 
-    if (!CddbWindow)
-        return FALSE;
+    g_return_val_if_fail (CddbWindow != NULL, FALSE);
 
     gtk_list_store_clear(CddbTrackListModel);
     Cddb_Set_Apply_Button_Sensitivity();
@@ -3725,8 +3723,8 @@ Cddb_Set_Track_Infos_To_File_List (void)
     GtkTreeIter *fileIter;
     gpointer iterptr;
 
-    if (!CddbWindow || !BrowserList || !ETCore->ETFileDisplayedList)
-        return FALSE;
+    g_return_val_if_fail (CddbWindow != NULL && BrowserList != NULL
+                          && ETCore->ETFileDisplayedList != NULL, FALSE);
 
     // Save the current displayed data
     ET_Save_File_Data_From_UI(ETCore->ETFileDisplayed);
diff --git a/src/et_core.c b/src/et_core.c
index d607f6e..a93ce17 100644
--- a/src/et_core.c
+++ b/src/et_core.c
@@ -3258,8 +3258,7 @@ ET_Save_File_Name_From_UI (ET_File *ETFile, File_Name *FileName)
     const gchar *filename_utf8;
     gchar *extension;
 
-    if (!ETFile || !FileName)
-        return FALSE;
+    g_return_val_if_fail (ETFile != NULL && FileName != NULL, FALSE);
 
     filename_utf8 = gtk_entry_get_text(GTK_ENTRY(FileEntry));
     filename = filename_from_display(filename_utf8);
@@ -3347,9 +3346,7 @@ ET_Save_File_Name_Internal (ET_File *ETFile, File_Name *FileName)
     gchar *extension;
     gchar *pos;
 
-
-    if (!ETFile || !FileName)
-        return FALSE;
+    g_return_val_if_fail (ETFile != NULL && FileName != NULL, FALSE);
 
     // Get the current path to the file
     dirname = g_path_get_dirname( ((File_Name *)ETFile->FileNameNew->data)->value );
@@ -3412,8 +3409,7 @@ ET_Save_File_Tag_From_UI (File_Tag *FileTag)
     //GtkTextIter    start_iter;
     //GtkTextIter    end_iter;
 
-    if (!FileTag)
-        return FALSE;
+    g_return_val_if_fail (FileTag != NULL, FALSE);
 
     /* Title */
     buffer = g_strdup(gtk_entry_get_text(GTK_ENTRY(TitleEntry)));
@@ -3650,8 +3646,8 @@ ET_Save_File_Tag_Internal (ET_File *ETFile, File_Tag *FileTag)
     File_Tag *FileTagCur;
 
 
-    if (!ETFile || !ETFile->FileTag || !FileTag)
-        return FALSE;
+    g_return_val_if_fail (ETFile != NULL && ETFile->FileTag != NULL
+                          && FileTag != NULL, FALSE);
 
     FileTagCur = (File_Tag *)ETFile->FileTag->data;
 
@@ -4251,8 +4247,7 @@ ET_Add_File_Name_To_List (ET_File *ETFile, File_Name *FileName)
 {
     GList *cut_list = NULL;
 
-    if (!ETFile || !FileName)
-        return FALSE;
+    g_return_val_if_fail (ETFile != NULL && FileName != NULL, FALSE);
 
     /* How it works : Cut the FileNameList list after the current item,
      * and appends it to the FileNameListBak list for saving the data.
@@ -4284,8 +4279,7 @@ ET_Add_File_Tag_To_List (ET_File *ETFile, File_Tag *FileTag)
 {
     GList *cut_list = NULL;
 
-    if (!ETFile || !FileTag)
-        return FALSE;
+    g_return_val_if_fail (ETFile != NULL && FileTag != NULL, FALSE);
 
     if (ETFile->FileTag)
     {
@@ -4788,8 +4782,7 @@ gboolean ET_File_Name_Convert_Character (gchar *filename_utf8)
 {
     gchar *character;
 
-    if (!filename_utf8)
-        return FALSE;
+    g_return_val_if_fail (filename_utf8 != NULL, FALSE);
 
     // Convert automatically the directory separator ('/' on LINUX and '\' on WIN32) to '-'.
     while ( (character=g_utf8_strchr(filename_utf8, -1, G_DIR_SEPARATOR))!=NULL )