all: support VMODULES environment variable (defaulting to ~/.vmodules)

cmd/tools/vpm.v

@@ -552,7 +552,7 @@ fn init_settings() {
 	s.is_help = '-h' in os.args || '--help' in os.args || 'help' in os.args
 	s.is_verbose = '-v' in os.args
 	s.server_urls = cmdline.options(os.args, '-server-url')
-	s.vmodules_path = os.join_path(os.home_dir(), '.vmodules')
+	s.vmodules_path = os.vmodules_dir()
 }
 
 fn verbose_println(s string) {

cmd/v/help/build.txt

@@ -54,7 +54,8 @@ The build flags are shared by the build and run commands:
       separated by pipes (`|`). In addition to absolute paths, you can
       also use these special strings too:
            @vmodules - replaced with the location of the global ~/.vmodules/ folder
-           (modules installed with `v install` are there).
+                       (modules installed with `v install` are there). You can change 
+                       its location by setting the environment variable VMODULES.
            @vlib - replaced with the location of the v's vlib folder.
       Using these, you can arrange for very flexible search orders for you project, for example:
            -path "/v/my_project_private_modules|@vlib|@vmodules"

vlib/os/os.v

@@ -1146,7 +1146,7 @@ pub fn real_path(fpath string) string {
 }
 
 fn normalize_drive_letter(path string) string {
-	// normalize_drive_letter is needed, because a path like c:\nv\.bin (note the small `c`) 
+	// normalize_drive_letter is needed, because a path like c:\nv\.bin (note the small `c`)
 	// in %PATH is NOT recognized by cmd.exe (and probably other programs too)...
 	// Capital drive letters do work fine.
 	$if !windows {
@@ -1355,6 +1355,15 @@ pub fn temp_dir() string {
 	return path
 }
 
+// vmodules_dir returns the path to a folder, where v stores its global modules.
+pub fn vmodules_dir() string {
+	mut path := os.getenv('VMODULES')
+	if path == '' {
+		path = os.join_path(os.home_dir(), '.vmodules')
+	}
+	return path
+}
+
 // chmod change file access attributes of `path` to `mode`.
 // Octals like `0o600` can be used.
 pub fn chmod(path string, mode int) {

vlib/v/builder/cc.v

@@ -637,11 +637,11 @@ fn (mut v Builder) cc() {
 }
 
 fn (mut b Builder) cc_linux_cross() {
-	parent_dir := os.join_path(os.home_dir(), '.vmodules')
+	parent_dir := os.vmodules_dir()
 	if !os.exists(parent_dir) {
 		os.mkdir(parent_dir)
 	}
-	sysroot := os.join_path(os.home_dir(), '.vmodules', 'linuxroot')
+	sysroot := os.join_path(os.vmodules_dir(), 'linuxroot')
 	if !os.is_dir(sysroot) {
 		println('Downloading files for Linux cross compilation (~18 MB)...')
 		zip_url := 'https://github.com/vlang/v/releases/download/0.1.27/linuxroot.zip'

vlib/v/doc/module.v

@@ -65,7 +65,7 @@ pub fn lookup_module_with_path(mod string, base_path string) ?string {
 	compile_dir := os.real_path(base_path)
 	modules_dir := os.join_path(compile_dir, 'modules', mod_path)
 	vlib_path := os.join_path(os.dir(@VEXE), 'vlib', mod_path)
-	vmodules_path := os.join_path(os.home_dir(), '.vmodules', mod_path)
+	vmodules_path := os.join_path(os.vmodules_dir(), mod_path)
 	paths := [modules_dir, vlib_path, vmodules_path]
 	for path in paths {
 		if !os.exists(path) || os.is_dir_empty(path) {

vlib/v/pref/default.v

@@ -7,13 +7,9 @@ import os
 import v.vcache
 
 pub const (
-	default_module_path = mpath()
+	default_module_path = os.vmodules_dir()
 )
 
-fn mpath() string {
-	return os.join_path(os.home_dir(), '.vmodules')
-}
-
 pub fn new_preferences() Preferences {
 	mut p := Preferences{}
 	p.fill_with_defaults()

vlib/v/util/util.v

@@ -299,7 +299,7 @@ fn non_empty(arg []string) []string {
 }
 
 pub fn check_module_is_installed(modulename string, is_verbose bool) ?bool {
-	mpath := os.join_path(os.home_dir(), '.vmodules', modulename)
+	mpath := os.join_path(os.vmodules_dir(), modulename)
 	mod_v_file := os.join_path(mpath, 'v.mod')
 	murl := 'https://github.com/vlang/$modulename'
 	if is_verbose {

vlib/v/vcache/vcache.v

@@ -36,7 +36,7 @@ pub mut:
 pub fn new_cache_manager(opts []string) CacheManager {
 	mut vcache_basepath := os.getenv('VCACHE')
 	if vcache_basepath == '' {
-		vcache_basepath = os.join_path(os.home_dir(), '.vmodules', 'cache')
+		vcache_basepath = os.join_path(os.vmodules_dir(), 'cache')
 	}
 	if !os.is_dir(vcache_basepath) {
 		os.mkdir_all(vcache_basepath)