Marked as friendly bug for newcomers, should be easy enough to add.

I'd like to work on this

(In reply to Anup Agarwal from comment #2)
> I'd like to work on this

A good place to look might gnome-documents, I think, since it's also written in JS and honors the --version option.

Created attachment 343223 [details] [review]
Add --version command line arguement

This commit address the bug:
https://bugzilla.gnome.org/show_bug.cgi?id=777020

In this bug a need for a --version command line arguement was raised.

Review of attachment 343223 [details] [review]:

Thanks!

::: src/application.js
@@ -282,2 +285,3 @@
     },
 
+    vfunc_handle_local_options: function(options) {

I think this could be handled in the same 'handle-local-options' signal handler as above, where the 'local' options is handled.

Review of attachment 343223 [details] [review]:

Thanks!

::: src/application.js
@@ -282,2 +285,3 @@
     },
 
+    vfunc_handle_local_options: function(options) {

I think this could be handled in the same 'handle-local-options' signal handler as above, where the 'local' options is handled.

Created attachment 343259 [details] [review]
Add --version command line arguement

This commit address the bug:
https://bugzilla.gnome.org/show_bug.cgi?id=777020

In this bug a need for a --version command line arguement was raised.

The version flag is handled in the same location where the local flag is handled
i.e.'handle-local-options' signal handler

Review of attachment 343259 [details] [review]:

Thanks!

::: src/application.js
@@ -107,2 +110,5 @@
                 this.local_tile_path = variant.deep_unpack();
                 normalStartup = false;
+            } else if (options.contains('version')) {
+                print(pkg.version);
+                return 0;

What happens when we return 0 and not -1? The program(instance) terminates? Could we get some comment about it?

What happens when a Maps window is already running and you go gnome-maps --version in the terminal?

Wow, that was fast. One addition, most Unix programs have [‑v] and [‑‑version] to show the version. Perhaps you can add the [‑v] too.

(In reply to tobias from comment #9)
> Wow, that was fast. One addition, most Unix programs have [‑v] and
> [‑‑version] to show the version. Perhaps you can add the [‑v] too.

Looking at the patch I think this is already the cacse, it adds both 'version' and 'v'.charAt(0) which will be the ascii value for 'v'.

(In reply to Jonas Danielsson from comment #8)
> Review of attachment 343259 [details] [review] [review]:
> 
> Thanks!
> 
> ::: src/application.js
> @@ -107,2 +110,5 @@
>                  this.local_tile_path = variant.deep_unpack();
>                  normalStartup = false;
> +            } else if (options.contains('version')) {
> +                print(pkg.version);
> +                return 0;
> 
> What happens when we return 0 and not -1? The program(instance) terminates?
> Could we get some comment about it?

Yes, -1 means "continue execution", and >=0 return using the UNIX exit code as
given (0 is success and >0 is interpreted as an error code typically).

> 
> What happens when a Maps window is already running and you go gnome-maps
> --version in the terminal?

(In reply to Jonas Danielsson from comment #8)
> Review of attachment 343259 [details] [review] [review]:
> 
> Thanks!
> 
> ::: src/application.js
> @@ -107,2 +110,5 @@
>                  this.local_tile_path = variant.deep_unpack();
>                  normalStartup = false;
> +            } else if (options.contains('version')) {
> +                print(pkg.version);
> +                return 0;
> 
> What happens when we return 0 and not -1? The program(instance) terminates?
> Could we get some comment about it?

Referring to:
https://developer.gnome.org/gio/2.42/GApplication.html#GApplication-handle-local-options 

The handler returns an exit code. If you have handled your options and want to exit the process, return a non-negative option, 0 for success, and a positive value for failure. To continue, return -1 to let the default option processing continue.

So if we are unable to handle options we return -1.
Also, I think for the local options since further processing needs to be done i.e. the mapView needs to launched with local tiles directory structure, thus -1 seems to be appropriate.

In the case of version since no other processing needs to be done thus 0 conforms with the exit code convention/requirement.

> 
> What happens when a Maps window is already running and you go gnome-maps
> --version in the terminal?

In such an event, the version of the package is printed in that particular terminal and the original Maps window is unaffected.

Thanks! Could you add a comment about this to the code?

Created attachment 360802 [details] [review]
application: Add --version command line arguement

Adds a --version command line option.
The version flag is handled in the same location where the local flag is handled
i.e.'handle-local-options' signal handler

Attachment 360802 [details] pushed as 93c08b3 - application: Add --version command line arguement