getEnv now supports a 'default' parameter; refs #6019

changelog.md

@@ -37,3 +37,5 @@
   This means its results are more precise and it can't run into an infinite loop
   anymore.
 - Added ``typetraits.$`` as an alias for ``typetraits.name``.
+- ``os.getEnv`` now takes an optional ``default`` parameter that tells ``getEnv``
+  what to return if the environment variable does not exist.

compiler/scriptconfig.nim

@@ -79,7 +79,7 @@ proc setupVM*(module: PSym; cache: IdentCache; scriptName: string;
     setResult(a, osproc.execCmd getString(a, 0))
 
   cbconf getEnv:
-    setResult(a, os.getEnv(a.getString 0))
+    setResult(a, os.getEnv(a.getString 0, a.getString 1))
   cbconf existsEnv:
     setResult(a, os.existsEnv(a.getString 0))
   cbconf dirExists:

compiler/vmops.nim

@@ -47,6 +47,11 @@ template wrap1s_ospaths(op) {.dirty.} =
     setResult(a, op(getString(a, 0)))
   ospathsop op
 
+template wrap2s_ospaths(op) {.dirty.} =
+  proc `op Wrapper`(a: VmArgs) {.nimcall.} =
+    setResult(a, op(getString(a, 0), getString(a, 1)))
+  ospathsop op
+
 template wrap1s_system(op) {.dirty.} =
   proc `op Wrapper`(a: VmArgs) {.nimcall.} =
     setResult(a, op(getString(a, 0)))
@@ -96,7 +101,7 @@ proc registerAdditionalOps*(c: PCtx) =
   wrap1f_math(ceil)
   wrap2f_math(fmod)
 
-  wrap1s_ospaths(getEnv)
+  wrap2s_ospaths(getEnv)
   wrap1s_ospaths(existsEnv)
   wrap1s_os(dirExists)
   wrap1s_os(fileExists)

lib/pure/includes/osenv.nim

@@ -94,7 +94,7 @@ proc findEnvVar(key: string): int =
     if startsWith(environment[i], temp): return i
   return -1
 
-proc getEnv*(key: string): TaintedString {.tags: [ReadEnvEffect].} =
+proc getEnv*(key: string, default = ""): TaintedString {.tags: [ReadEnvEffect].} =
   ## Returns the value of the `environment variable`:idx: named `key`.
   ##
   ## If the variable does not exist, "" is returned. To distinguish
@@ -108,7 +108,7 @@ proc getEnv*(key: string): TaintedString {.tags: [ReadEnvEffect].} =
       return TaintedString(substr(environment[i], find(environment[i], '=')+1))
     else:
       var env = c_getenv(key)
-      if env == nil: return TaintedString("")
+      if env == nil: return TaintedString(default)
       result = TaintedString($env)
 
 proc existsEnv*(key: string): bool {.tags: [ReadEnvEffect].} =

lib/system/nimscript.nim

@@ -106,7 +106,7 @@ proc cmpic*(a, b: string): int =
   ## Compares `a` and `b` ignoring case.
   cmpIgnoreCase(a, b)
 
-proc getEnv*(key: string): string {.tags: [ReadIOEffect].} =
+proc getEnv*(key: string; default = ""): string {.tags: [ReadIOEffect].} =
   ## Retrieves the environment variable of name `key`.
   builtin