According to this tutorial, when defining routes in Angular for Dart you need to import the template.dart files of the relevant components:
import 'crisis_list_component.template.dart' as clct;
import 'hero_list_component.template.dart' as hlct;
I have put my components in a subfolder of the folder where this code resides. I have the import code in lib/src/routes.dart:
import 'components/foobar/foobar_component.template.dart' as fct;
and a Foobar component in lib/src/components/foobar/foorbar_component.dart.
When I have the foobar_component.dart code in src (i.e. the same folder as routes.dart) there's no problem. But when I move it to its own subfolder, I get the error:
Unable to find modules for some sources [...] Please check the following imports: import 'components/foobar/foobar_component.template.dart'
How do I get it to find the component in its subfolder?
You could use
import '../../components/foobar/foobar_component.template.dart' as fct;
but usually, it is better to not use ../ in imports and instead use package imports
import 'package:my_package/web/src/components/foobar/foobar_component.template.dart' as fct;
where my_package is the string used in name: ... in your pubspec.yaml and lib/ is skipped in the path to the imported file.
Related
I develop a flutter app, define serveral models in 'model' package.
Then I declare a class Example in 'model' for example.
model/example.dart
class Example {
#override
String toString() {
return 'class example';
}
}
test_a.dart
import 'package:example/model/example.dart'
Example testA() {
return Example()
}
test.dart
import 'model/example.dart'
import 'test_a.dart'
test() {
Example example = testA();
if (example is Example) {
print('this class is Example');
} else {
print('$example');
}
}
I will get output class example🌚
If I change from import 'model/example.dart' to import 'package:example/model/example.dart' in test.dart, then I will get the output this class is Example.
So I'm confused what is different between the full path and relative path in dart.
package imports
'package:... imports work from everywhere to import files from lib/*.
relative imports
Relative imports are always relative to the importing file.
If lib/model/test.dart imports 'example.dart', it imports lib/model/example.dart.
If you want to import test/model_tests/fixture.dart from any file within test/*, you can only use relative imports because package imports always assume lib/.
This also applies for all other non-lib/ top-level directories like drive_test/, example/, tool/, ...
lib/main.dart
There is currently a known issue with entry-point files in lib/* like lib/main.dart in Flutter. https://github.com/dart-lang/sdk/issues/33076
Dart always assumed entry-point files to be in other top-level directories then lib/ (like bin/, web/, tool/, example/, ...).
Flutter broke this assumption.
Therefore you currently must not use relative imports in entry-point files inside lib/
See also
How to reference another file in Dart?
how to import (de.polygonal.graphics.VectorRenderer)
in this link http://lab.polygonal.de/?p=916 this is the component https://github.com/polygonal/gl
Add the package/class to the path of your .fla file, if you're using Flash Professional. Otherwise, add it to the root of the project.
** This question is edited and cleaned up some **
I have two projects and I want to use code from one in the other; I seem to be having trouble putting the code in the right directory structure to make the import statements work.
Both projects are created and managed exclusively from the Dart Editor on a Mac, if that makes any differences.
Project Directory Structures
Project 1: a command line app which contains the code I want to share in the following directory structure:
/dart/command_line_app
/lib
shared_library.dart
/bin
command_line_app.dart
Project 2: a web app which wants to import the code in shared_libary.dart
/dart/web_application
/packages
/web
web_application.dart
In the file shared_libary.dart, I declare it to be a library can create a simple class that provides output when instantiated:
library shared_library;
class ShareMe
{
ShareMe()
{
print("Hello, ShareMe");
}
}
This compiles, and works inside the command_line project: command_line_app.dart has the following:
import 'package:command_line_app/shared_library.dart';
void main() {
ShareMe shareMe = new ShareMe();
print("Hello, World!");
}
This imports the code runs, printing both "Hello Share Me," and Hello World.
THE PROBLEM
I want to instantiate the ShareMe class inside web_application.dart. I'd thought I could do that by putting in the same import statement I put in my command_line code:
import 'package:command_line_app/shared_library.dart';
But, when I put the same import into the web_appliation, it gets the error
Target of URI does not exist 'package:command_line_app/shared_library.dart'
Other Things I've Tried
I was certain I'd solved the problem when I cntrl-Clicked properties on Web_application and selected Project References.
It brings up a window allowing me to select command_line_app with a check box, but when I do, I get an error:
Could not set the project description for 'web_application' because the project description file (.project) is out of sync with the file system.
Whatever that means.
When I cntrl-click the underlined error and try Quick Fix it offers me "resolve dependencies" which sounds promising, but after a few seconds, it comes back and informs me that
Pub get failed, [1] Resolving dependencies... (15.3s)
Could not find package command_line_app at https://pub.dartlang.org.
Depended on by:
- web_application 0.0.0
I hope this is clear-er and gives a better insight into both what I'm trying to do and what I'm missing.
EDIT
you need to add
dependencies:
command_line_app:
path: ../command_line_app
to your dependencies in web_application/pubspec.yaml.
EDIT END
When you want to make code reusable in different packages, you should put that code into the lib directory of that package and import it using import 'package:mypackage/myfile.dart';.
Another problem you may face is, that browser applications can't import packages that have a dart:io dependency. If you want to reuse code between command line and browser applications you should move them into the lib directory of another package my_shared_code where you put only code that doesn't depend on dart:io (for example some entity classes) and import this code from both app packages (browser and command line).
Say, I load this script in the browser:
<script src='app.dart' type='application/dart'></script>
Now, in app.dart I have this:
import 'library1.dart';
unleashTheKraken();
Then in library1.dart you'll find this:
library library1;
import 'library2';
And finally in library2.dart we'll have:
library library2;
unleashTheKraken() => print('Unleashing the Kraken')
And the result is: Exception: No top-level method 'unleashTheKraken' declared. How so?
Because imports don't chain automatically. You have to use the export statement for that.
library library1;
import "library2.dart";
export "library2.dart";
And to avoid unnecessary code: import and export are completely independent. If you don't use unleashTheKraken in library1 itself, you can omit the import statement and just use export alone.
I know you can use the library, import and even #import, but which is correct?
I have got two files, MainClass.dart and Library.Dart, and I want to add a reference to Library.dart in MainClass.dart. How can I do that?
Firstly let me just preface this by saying please do not use the hash symbol before import or library or anything else. This is an old syntax that is being deprecated. So we no longer want to use #import('...') The correct syntax is:
import 'some_file.dart';
That said, there are two different things we can do to access different dart source files within our current file. The first is to import the file. We use this such as in your case when you want to bring a different library into the current file (or more accurately current library).
Usually if your files are in the same directory, or a sub directory of the current one we would import them like this:
import 'lib/library.dart';
However If you are using the pub package layout you can also use some special short-cut references as well to import files (particularly from other packages you've imported). I highly suggest reading the documents on the pub site, as most applications and libraries are designed with this in mind. It also has suggestions on best naming conventions such as filenames in all lower case, and using underscore for spaces, and directory layouts.
The other important thing to know about bringing a dart file into another file, is that we can use the part and part of directives. This used to be called #source but was changed (with the removal of the hash sign) to reduce confusion. The part directive is used when we want to write a single library which spans multiple files. Say for instance you have an Awesome Library, which is starting to get a little large for a single file. We will create the main file of the library (not to be confused with the main method). This file will usually have the same name as the library itself.
// awesome_library.dart
library awesome_library;
import 'dart:math';
import '...';
// this injects all the content of secret_file.dart
// into this file right here almost as if it was
// here in the first place.
part 'src/secret_file.dart';
// The rest of our file here
// ...
The part directive basically takes everything from our src/secret_file.dart and inserts it into that part of the file. This allows us to split our huge Awesome Library into multiple smaller files that are easier to maintain. While not specifically required, it is helpful to use the part of directive in our secret_file.dart to help the editor know that it is "part of" the library.
// secret_file.dart
part of awesome_library;
// ... Rest of our secret_file code below.
Note that when using a part file like this, the part(s) (that is everything that is not the main file of the library) cannot import or use library declarations themselves. They import whatever is imported into the the main file, but they cannot add any additional imports.
For more information about library see this link.
Importing your own created libraries:
You will be importing the filename.dart and not the name of your library.
So if the name of your library is: myLib and it is saved in the file: someDartFile.dart you will have to
import 'someDartFile.dart';
If you have on Windows a library at: K:\SomeDir\someFile.dart you will need to write:
import '/K:/SomeDir/someFile.dart';
example:
import 'LibraryFile.dart'; //importing myLib
void main(){
//a class from myLib in the LibraryFile.dart file
var some = new SomeClassFromMyLibrary();
}
myLib in LibraryFile.dart:
library myLibrary;
import 'dart:math';
class SomeClassFromMyLibrary{
String _str = "this is some private String only to myLibrary";
String pubStr = "created instances of this class can access";
}
Here a full example.
//TestLib.dart
import 'LibFile.dart'; //SomeLibrary
void main() {
print("Hello, World!");
LibFile l = new LibFile();
print(l.publicString);//public
print(l.getPrivateString);//private
print(l.getMagicNumber); //42
}
//LibFile.dart
library SomeLibrary;
part 'LibFile2.dart';
class LibFile {
String _privateString = "private";
String publicString = "public";
String get getPrivateString => _privateString;
int get getMagicNumber => new LibFile2().number;
}
//LibFile2.dart
part of SomeLibrary;
class LibFile2 {
int number = 42;
}
Although i am answering very late, but the answer may help new developer.
Always use pubspec.yaml file in your dart package(application/library).
once you run pub get command it will add your local library in the dependencies list in .packages file.
Consider i have following project structure.
To refer to the content of greeting.dart in my main.dart file i should add the library as below
import 'package:my_project_name/greeting.dart'
Once imported we can use the content of greeting.dart file in our main.dart file.
Note: we have not used the actual path as you can see 'lib' directory is missing.
First make sure that's the name which you have mentioned in pubspec.yaml and the file you want to import are sharing the exact same name
example:
pubspec.yaml
name: flutter_wordpress_app
description: flutter wordpress app
...
....
// dirOne/dirTwo/greeting.dart
class FavArticleBloc {
// Your code goes here
}
import 'package:flutter_wordpress_app/dirOne/dirTwo/greeting.dart'
void main(){
var some = new FavArticleBloc();
}
But
in the main.dartyou don't need to specify
import 'package:flutter_wordpress_app
just do like below
import 'dirOne/dirTwo/greeting.dart