# [PATCH] do not discard constness in interp_set_entry value argument

1 messages from 2006-09-28 to 2006-09-28. Participants: Alex Riesen.
Thread: https://gitlist.dev/t/5744

## Alex Riesen, 2006-09-28 19:12

Subject: [PATCH] do not discard constness in interp_set_entry value argument
Message-ID: <20060928191255.GB4294@steel.home>
URL: https://gitlist.dev/e/20060928191255.GB4294%40steel.home

```
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>

---

Actually, both of the struct interp's fields could be made const,
if not this interp_set_entry. And even then it could just return
the old value of ->value casting away its constness. I.e.:

struct interp
{
    const char *name;
    const char *value;
};

static inline char *interp_set_entry(struct interp *table, int slot, const char *value)
{
	char *oldval = (char *)table[slot].value;

	table[slot].value = newval;
	return oldval;
}

The caller can than decide if it should be freed. This leaves
compiler with a chance to optimize something.

diff --git a/interpolate.c b/interpolate.c
index 62701d8..5d9d188 100644
--- a/interpolate.c
+++ b/interpolate.c
@@ -8,10 +8,10 @@ #include "git-compat-util.h"
 #include "interpolate.h"
 
 
-void interp_set_entry(struct interp *table, int slot, char *value)
+void interp_set_entry(struct interp *table, int slot, const char *value)
 {
 	char *oldval = table[slot].value;
-	char *newval = value;
+	char *newval = NULL;
 
 	if (oldval)
 		free(oldval);
diff --git a/interpolate.h b/interpolate.h
index a55fb8e..190a180 100644
--- a/interpolate.h
+++ b/interpolate.h
@@ -16,7 +16,7 @@ struct interp {
 	char *value;
 };
 
-extern void interp_set_entry(struct interp *table, int slot, char *value);
+extern void interp_set_entry(struct interp *table, int slot, const char *value);
 extern void interp_clear_table(struct interp *table, int ninterps);
 
 extern int interpolate(char *result, int reslen,

```