angular-docs-cn/packages/compiler-cli/ngcc
Misko Hevery 70962465b5 fix(core): Switch `emitDistinctChangesOnlyDefaultValue` to true (#41121)
BREAKING CHANGE:

Switching default of `emitDistinctChangesOnlyDefaultValue`
which changes the default behavior and may cause some applications which
rely on the incorrect behavior to fail.

`emitDistinctChangesOnly` flag has also been deprecated and will be
removed in a future major release.

The previous implementation would fire changes `QueryList.changes.subscribe`
whenever the `QueryList` was recomputed. This resulted in an artificially
high number of change notifications, as it is possible that recomputing
`QueryList` results in the same list. When the `QueryList` gets recomputed
is an implementation detail, and it should not be the thing that determines
how often change event should fire.

Unfortunately, fixing the behavior outright caused too many existing
applications to fail. For this reason, Angular considers this fix a
breaking fix and has introduced a flag in `@ContentChildren` and
`@ViewChildren`, that controls the behavior.

```
export class QueryCompWithStrictChangeEmitParent {
  @ContentChildren('foo', {
    // This option is the new default with this change.
    emitDistinctChangesOnly: true,
  })
  foos!: QueryList<any>;
}
```
For backward compatibility before v12
`emitDistinctChangesOnlyDefaultValue` was set to `false. This change
changes the default to `true`.

PR Close #41121
2021-03-12 10:47:56 -08:00
..
src perf(compiler-cli): use bound symbol in import graph in favor of module resolution (#40948) 2021-03-08 12:05:48 -08:00
test fix(core): Switch `emitDistinctChangesOnlyDefaultValue` to true (#41121) 2021-03-12 10:47:56 -08:00
BUILD.bazel perf(compiler-cli): detect semantic changes and their effect on an incremental rebuild (#40947) 2021-03-08 08:41:19 -08:00
README.md refactor(ivy): move ngcc into a higher level folder (#29092) 2019-03-20 14:45:54 -04:00
index.ts refactor(ngcc): move `logging` code into `ngtsc` (#37114) 2020-06-22 13:38:47 -07:00
main-ivy-ngcc.ts build: update license headers to reference Google LLC (#37205) 2020-05-26 14:26:58 -04:00
main-ngcc.ts build: update license headers to reference Google LLC (#37205) 2020-05-26 14:26:58 -04:00

README.md

Angular Compatibility Compiler (ngcc)

This compiler will convert node_modules compiled with ngc, into node_modules which appear to have been compiled with ngtsc.

This conversion will allow such "legacy" packages to be used by the Ivy rendering engine.

Building

The project is built using Bazel:

yarn bazel build //packages/compiler-cli/ngcc

Unit Testing

The unit tests are built and run using Bazel:

yarn bazel test //packages/compiler-cli/ngcc/test

Integration Testing

There are tests that check the behavior of the overall executable:

yarn bazel test //packages/compiler-cli/ngcc/test:integration