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In my dart project projectxyz, I have a dart class declared in in myclass.dart. In main.dart, Android Studio gives two ways, both work, but I did not understand what are the pros and cons of each method:
import 'myclass.dart';
or:
import 'package:projectxyz/myclass.dart';
What is the difference in these two approaches?
That depends on how the main file itself is invoked (and where it's located).
I'll assume the main.dart library is inside the lib/ directory, because otherwise you wouldn't have the two options for importing myclass.dart.
If you invoke the main file with a file: URI, then the relative import of myclass.dart will also be imported with a file: URI. Since Dart uses the import URI to distinguish different libraries, if someone else imports myclass.dart using a package: URI, then it will be treated as two different libraries introducing different classes with the same name.
It used to be that running dart lib/main.dart would treat that as a file: URI. The Dart parser has gotten smarter about that, and now it recognizes that an entry point library in a lib/ directory should have been a package: URI, and replaces the entry point URI with package:projectxyz/main.dart.
After that, it makes no difference whether you use myclass.dart or package:projectxyz/myclass.dart.
Really, there is no difference between the two. Saying import 'myclass.dart' is high-level sugar for import 'package:projectxyz/myclass.dart';.
On the other hand, import 'myclass.dart' is easier to read and understand, and generally looks better. It also decreases confusion as to where exactly your code is being imported from, as anybody who reads this statement knows to look for the file elsewhere in your project. Because of this, you should try to use this form wherever possible.
I am very new to F# and trying to convert my python script to F# code for my learning.
i want to parse multiple (around 25 files) static html files to extract similar information from each file.
I want to have a list of file handle for all the html files.
I am able to do it for single file as:
type SummaryHtmlType = HtmlProvider< #"C:/MyLocation/Summary_1.html">
I tried something similar to XmlProvider (even not sure if that's correct for XmlProvider), but no success.
type MyType = HtmlProvider<htmlFileList; SampleIsList=true>
Let me know solution even if there is all together different approach to do it.
"C:/MyLocation/Summary_1.html" in type SummaryHtmlType = HtmlProvider< #"C:/MyLocation/Summary_1.html"> is a sample file for HtmlProvider get the basic structure.
To parse file or url, use Load method like SummaryHtmlType.Load(url)
For more information, see http://fsharp.github.io/FSharp.Data/library/HtmlProvider.html
Yes, I read dart import and part of directives in same file
I have this structure:
lib/
src/
one/
SomeClass.dart
one.dart
mylib.dart
main.dart
I'm trying to achieve this behavior:
All public and hidden variables are fully accessible inside library.
All public variables from library are accessible to main.dart.
There is a problem. For some weird reason I can't use any directive with 'part of'. So I can't use this in the one.dart:
part of mylib;
import 'SomeClass.dart';
//somecode
So I either need to move class definition from SomeClass.dart to one.dart (and that will make code less readable and mixed up) or I need to move 'import' in the mylib.dart.
library mylib;
import 'SomeClass.dart';
part ..
I don't like either of the options. In the second case I will need to parse all modules then and move import/exports. Which will definitely break something.
It may sound weird but the project will build from various modules automatically. And one/ is one of them.
This app design is bad, I know. But either I need to find a better way or just make all variables public and don't bother.
Default to defining one type per file, not using part, and importing only the files you need. This covers the majority of use cases.
Now, let's say you have two types that are commonly used together - for example, a Thing and a ThingException that gets thrown when Thing does bad things. Importing both of these files everywhere is tedious, so you have three options with their own tradeoffs:
Declare both types in the same file.
Declare each type in its own file, and have the 'primary' file export the other. So, thing.dart exports thing_exception.dart. Importing thing.dart gives the importing file access to both.
Declare each type in its own file, and have the other file be a 'part of' the primary file. So, thing_exception.dart declares that it is 'part of' thing.dart. Importing thing.dart gives the importing file access to both files.
For this simple type and its exception, your best bet is to use option 1. When the amount of code grows or the two types diverge in visibility, this option becomes less attractive. This puts options 2 and 3 are on the table.
When you have separate files, option 2 is often a better approach than options 3 because you maintain some flexibility - you could only import thing_exception.dart and not thing.dart. If you use option 3, you can't do this - you either import all of the parts or none of them. This is the error you are seeing when trying to do a part and import in the same file.
Option 3 becomes valuable when you the code is in the two files is highly dependent on one another and they need the ability to access private members of each other. This is less common.
When you have a bunch of files like this together, it becomes a 'library' in the more traditional sense. You declare a main library file (your my lib.dart file) that exports files:
export 'public.dart';
export 'other_public.dart';
The bin script imports the library as a whole, but it can't see anything that isn't explicitly exported from my_lib.dart.
import 'package:mylib/mylib.dart';
Here's an example of a smallish package that uses all three of these options together for a good reference.
I think you will have better luck using import, and export with show. (Use of part of is now discouraged.)
Answers to this question may help you: When to use part/part of versus import/export in Dart?
Also the Creating library packages documentation: https://www.dartlang.org/guides/libraries/create-library-packages
I'm trying to read in the text (as a string) of an XML file from my Resources. The XML file is named MyXMLResourceFile.resx.
I tried using the C# way using
let myFile : string = Properties.Resources.MyXMLResourceFile
but it is giving me the error (under Properties):
The namespace or module 'Properties' is not defined.
I'm assuming I'm missing an open but have no idea what it would be.
Sorry, I'm still pretty new to F# coming from VB.
Additional information:
I made the resx file myself per this SO answer I then looked to see how others accessed it. In C# they did Properties.Resources.XXXX per this project I saw you could use ResourceManager but didn't see any method to read the whole file directly into a string.
The namespace or module 'Properties' is not defined.
That's because the namespace Properties is not defined. You probably brought the resx file from another project. Open the associated .Designer file, if it doesn't appear in the F# project, open it up in the original project. You will see a namespace with and a bunch of C# code, assuming the original project was in C#. The namespace of this file has to be the same namespace of the project where you are trying to call it.
But, since this is C# code, it won't run on a F# project. You have two choices: use a code generator to generate the associated .Designer class in F# code with the Properties namespace, (I don't know if such generator exists); or pre-compile the resx in the original project and reference it as a dll from your F# project, then you can access it with ResourceManager.
I have a custom external XJB file that has the schema name within it as follows :
jxb:bindings schemaLocation="completeCheck.xsd" node="/xs:schema"
Just wondering, is there a way to substitute the schema name at runtime within the XJB file using ANT(using ANT XJC) OR have a xjb binding file written such that I do not have to hardcode the schema name in it. Basically, I am trying to see if I can use a single xjb file for multiple XSDs.
Currently, I have the same xjb file all over the place with a different hardcoded schema name referred all over the place in build.xml. Any pointers are highly appreciated. I am using JAXB 2.x
Make a template from your xjb file by replacing the value of your schemaLocation attribute with some sort of marker (e.g. !!!) and save it using some other name/extension. Define a macro with an attribute such as schema-name that will use ant's replace to change the marker in the template file with your schema name and save that as the binding file to be subsequently used by xjc.
Normally, in the latest versions of XJC, you can use schema component designator. More info here :
https://jaxb.java.net/nonav/2.2.1/docs/vendorCustomizations.html#scd and https://jaxb.java.net/guide/Using_SCD_for_customizations.html