Strong mode code excerpt tests for fix-it page #603
Conversation
chalin
added
infra.structure
googlebot
added
the
cla: yes
chalin
force-pushed
the
chalin-strong-mode-common-problems-0221
branch
from
0fb637b
to
8cca216
Compare
| {% comment %} | ||
| NOTE TO Kathy: I don't think that we should recommend use of dynamic in this case, | ||
| so I'm commenting this out. WDYT? | ||
|
|
There was a problem hiding this comment.
Is there a similar case where you would want dynamic?
There was a problem hiding this comment.
While not for this specific example, there are similar situations where we'd like to be able to write a union type but can't. I'll tweak the code and include the example using dynamic.
| NOTE TO Kathy: I think that we should consider renaming this section. How about | ||
| <a id ="assigning-mismatched-types"></a> | ||
| ### Unexpected collection element type | ||
|
|
| error • The getter 'context2D' isn't defined for the class 'Element' • undefined_getter | ||
| ``` | ||
|
|
||
| #### **Fix**: Replace the definition of the member with an explicit type declaration or a downcast |
There was a problem hiding this comment.
Let's not boldface "Fix" (global).
| class Animal { | ||
| void chase(Animal x) {} | ||
| void chase(Animal x) { ... } |
There was a problem hiding this comment.
It'd be nice to use the NumberAdder example instead of Animal.
There was a problem hiding this comment.
Ok, but why do you feel it would be better? (I'll leave the Animal hierarchy for now.)
There was a problem hiding this comment.
Because the link is from the section that has the NumberAdder example. It's a bit jarring to switch to another example.
|
|
||
| This sometimes happens when you create a simple dynamic collection | ||
| and the analyzer Dart infers the type in a way you didn't expect. | ||
| and the analyzer infers the type in a way you didn't expect. | ||
| When you later add values of a different type, | ||
| the analyzer produces a warning. |
| @@ -175,45 +208,56 @@ to specify a type. For more information, see | |||
| [Missing type arguments](#missing-type-arguments). | |||
| </aside> | |||
|
|
|||
There was a problem hiding this comment.
Above, the note says "warning" but should say "error" or "issue".
| For example, the following code initializes a map with several | ||
| (String, integer) pairs. The analyzer infers that map to be of type | ||
| The following code initializes a map with several | ||
| (String, int) pairs. The analyzer infers that map to be of type | ||
| `<String, int>` but the code assumes `<String, dynamic>`. |
There was a problem hiding this comment.
I'd argue that it assumes <String, num>, which matches the suggested fix. Maybe:
...<String, int>, but the code seems to assume either <String, dynamic> or <String, num>.
| However, in Dart 2 passing something other than `dynamic` (or another _top_ | ||
| type, such as `Object`, or a specific bottom type, such as `Null`) fails at | ||
| compile-time (called `uses_dynamic_as_bottom`): | ||
| compile-time. |
There was a problem hiding this comment.
This is just a warning, not an error, so does it really fail?
|
|
||
| One fix could be, if possible, typing `Filter` as `Filter<T>`: | ||
| When possible, fix this error by adding type parameters: |
There was a problem hiding this comment.
fix this error -> avoid this warning
?
| different than the variable's static type. Like most modern statically | ||
| typed langauges, Dart accomplishes this with a mixture of static | ||
| typed langauges, Dart accomplishes this with a combination of static |
atsansone
added
dev.null-safety
Contributes to #407
Staged at https://dartlang-org-staging-0.firebaseapp.com/guides/language/sound-problems
Each of the static warnings/errors now has:
E.g.,