[gjs] package: Add requireSymbol() method

[Philip Chimento <pchimento src gnome org>]

commit ca34972ee1e853bd1034584441fd258e6c390ac6
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Mar 3 21:01:21 2017 +0100

    package: Add requireSymbol() method
    
    While the existing require() method provides a convenient way
    to check for hard dependencies, it only tests whether a particular
    typelib can be imported. The newly added checkSymbol() method on
    the other hand allows for finer-grained tests, but leaves it to
    the caller to check the return value. Fill that gap by providing
    a requireSymbol() method that wraps checkSymbol() to error out
    when the dependency is not satisfied.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=779593

 modules/package.js |   27 ++++++++++++++++-----------
 1 files changed, 16 insertions(+), 11 deletions(-)
---
diff --git a/modules/package.js b/modules/package.js
index 03fceaa..5a5cd22 100644
--- a/modules/package.js
+++ b/modules/package.js
@@ -232,18 +232,23 @@ function run(module) {
  * indicates any version.
  */
 function require(libs) {
-    for (let l in libs) {
-        let version = libs[l];
-
-        if (version != '')
-            imports.gi.versions[l] = version;
+    for (let l in libs)
+        requireSymbol(l, libs[l]);
+}
 
-        try {
-            imports.gi[l];
-        } catch(e) {
-            printerr('Unsatisfied dependency: ' + e.message);
-            System.exit(1);
-        }
+/**
+ * requireSymbol:
+ *
+ * As checkSymbol(), but exit with an error if the
+ * dependency cannot be satisfied.
+ */
+function requireSymbol(lib, version, symbol) {
+    if (!checkSymbol(lib, version, symbol)) {
+        if (symbol)
+            printerr(`Unsatisfied dependency: No ${symbol} in ${lib}`);
+        else
+            printerr(`Unsatisfied dependency: ${lib}`);
+        System.exit(1);
     }
 }