remove method setId() from core/lib/Drupal/Core/Language/LanguageInterface

I think we need add some more comment to Language.id, why there's no setter for it.

@thehong hm. Maybe, but this is a common pattern already in core. (of having an id property, a id() function (getter) and no setter).

If we wanted to add a comment explaining that id was immutable and has no setter on purpose... it would be a separate issue to find all the classes that have a protected id which does not have a setter, and add a similar comment to all of them.

I agree with the thrust of the issue...

In terms of review....

1) The implementation makes complete sense.
2) The immutability argument in #12 follows a recognizable established pattern.
3) After a slow and steady scan of the patch - nothing is out scope or inappropriate.

So +1 from me.

+++ b/core/tests/Drupal/Tests/Core/Language/LanguageUnitTest.php
@@ -47,12 +47,11 @@ public function testGetName() {
+    $language = new Language(array('id'=>$language_code));

@@ -115,20 +114,17 @@ public function testSortArrayOfLanguages(array $languages, array $expected) {
+    $language9A = new Language(array('id'=>'dd'));
...
+    $language10A = new Language(array('id'=>'ee'));
...
+    $language10B = new Language(array('id'=>'ff'));

I think this is small issue with coding standard, should change to array('key' => 'value')

@thehong forgive me but I don't understand what you are saying.

@martin107, the patch is just missing spaces around '=>'. Please check more at https://www.drupal.org/coding-standards#array

Ah thank you ... fixed.

Much more sense. RTBC.

Regret.

+++ b/core/tests/Drupal/Tests/Core/Language/LanguageUnitTest.php
@@ -47,12 +47,11 @@ public function testGetName() {
   public function testGetLangcode() {
     $language_code = $this->randomMachineName(2);
-    $this->assertSame($this->language, $this->language->setId($language_code));
-    $this->assertSame($language_code, $this->language->getId());
...
+    $this->assertSame($language_code, $language->getId());
   }

Can we use $this->language per consistence with the other tests?

Committed 4b42df3 and pushed to 8.0.x. Thanks!

@penyaskito don't think that matters - it's a test - file a followup issue if you like.