Rory Becker - DevExpress CodeRush Blog

April 2014 - Posts

  • New CodeRush Plugin Template – NewContext

    What is context?

    The circumstances that form the setting for an event, statement, or idea, and in terms of which it can be fully understood.

    What does CodeRush use context for?

    CodeRush uses context (in addition to user input) to decide which functionality to provide you with.

    For example: The <Tab> key is used for indenting text, and also for invoking the Tab to Next Reference (TtNR) feature. When you hit the <Tab> key, CodeRush performs several context checks.

    The context settings for TtNR are fairly complicated, but boils down to IsTheCaretWithinAnIdentifier. If CodeRush judges that this is the case, then it chooses the TtNR functionality, otherwise it chooses the indentation functionality.

    CodeRush Templates and Shortcuts often overload each other in this way, and CodeRush uses the context to determine which overload to use.

    How do I use a context?

    You don’t use a context directly. Instead you choose a feature which is sensitive to context (a shortcut or template will do nicely) and configure it to only work within a given context (or set of contexts)

    Features can be configured to work with a specific context where ever you see this UI.

    ContextPicker

    Each node in the tree is a context. The contexts will either be true or false at a given moment.

    When being tested, a ticked context will be tested at the moment of invocation and the feature\function will only be allowed if that context is found to be true. Alternatively if the context has a cross against it, then the function\feature will only be allowed to proceed if the context is explicitly found to be false.

    What if I can’t find the context I need?

    Well first of all I recommend contacting support@devexpress.com since it’s entirely possible that the context you’re after is there, but perhaps not named or located as you would expect. However, failing that, it is very easy to create a brand new context in a plugin.

    How do I create a context?

    Contexts are analogous to functions which return a boolean value. You check anything you like, (Source code, Project structure, color of the moon) and then set the context to true or false accordingly.

    Creating a context is really really simple… just use the NewContext template. Note This template does not ship with CodeRush. See instructions later in this post for how to acquire the template.

    Once you have the template installed, simply position your caret in the body of your plugin and type NewContext<space>

    The Template will expand like so…

    NewContextTemplate

    You will then need to fill out a few details.

    • A Component Name
      This first name is used to identify the metric component itself within your code. You might be about to create several of these and they all need to be distinct from one another and their methods not confused.
    • A Display Name
      The display name is a short identifier used whenever a group of contexts are listed together to distinguish them from each other.
    • A Description
      Explains to the user ticking or crossing the context, what the context is looking for in order to be considered satisfied.
    • A Provider Name
      This is the path at which the context will be listed. A backslash separated set of strings is required here. ie Editor\XML\InOpenTag

    With these properties filled out, all you need to do is…

    • Implement the ContextSatisfied method
      Perform whatever calculations and discovery you like and then set ea.Satisfied = true; when your context is satisfied
    • Call Register
      Call your newly generated Register method from within your InitializePlugin method.

    Where can I get this template?

    As usual this template is available from within the CodeRush Plugin Templates repository on github

    Download and Import this file using these instructions

    Or if you’ve installed the Template Importer, simply point it at this webaddress and click import.

  • Community Callout: New CodeRush Plugin CR_FluentPoco

    Richard O’Neil, author of the FakeItEasy CodeRush Templates has been at it again.

    This time he’s taken a step up, and built a new CodeRush plugin.

    From his github repository:

    CodeRush expansion plugin to turn a list of private fields into fluent methods.

    I created this to help me build helper classes for an automated testing framework I was making with Selenium and it's WebDriver.

    If you start with code like this…
    CR_FluentPocoStartClass
    

    The generated code will enable you make the following call…
    CR_FluentPocoExampleFluentCall

    Naturally Richard has open sourced his creation for all the world to use, so head on over and give him some feedback.

    For more information see the CR_FluentPoco repository on GitHub

  • New CodeRush Plugin – Add Data Contract – How does it work?

    In my last post I presented the Add DataContract plugin.

    In this post I’ll walk you through what makes it tick.

    Overview

    In essence there are 3 parts to this plugin

    • Add the Namespace Reference (Imports\using directive)
    • Add the DataContract attribute to the class.
    • Add the DataMember attribute to each of the classes properties.

    Structure

    The Add Data Contract plugin is a CodeProvider with the usual CheckAvailability and Apply methods. The basic plumbing of this plugin is created with the NewCodeProvider CodeRush template detailed in this blogpost.

    Add Namespace

    In the DXCore, a using directive (or an imports directive in VB.Net) is called a NamespaceReference

    To add a NamespaceReference to the current file it is first necessary to determine if one already exists. For this we construct a new ElementEnumerable capable of searching the current file for NamespaceReference objects. This is then used to return an IEnumerable<NamespaceReference>

    AddDataContractGetNamespaceReferences

    The list of namespace is queried to determine if the new namespace is already referenced. There is nothing to be gained by referencing the same namespace twice. If it is found, then we return from the apply method without having performed any modifications.

    AddDataContractExitIfNamespaceAlreadyPresent

    Location, Location, Location

    Next we determine the best location to insert our NamespaceReference.

    If there are no existing NamespaceReferences, then the InsertionPoint is set to the start of the current document.

    Alternatively, if there are some pre-existing NamespaceReferences, then the start of the last of these is picked as a sensible default.AddDataContractDetermineNamespaceInsertionPoint

    Code Generation and Insertion

    Next we create our new NamespaceReference object (passing in the string representing the namespace in question) and have CodeRush generate the actual code that represents this object. The last step in generating our NamespaceReference is to queue the insertion of this code at the InsertionPoint determined in the previous step

    AddDataContractGenerateCodeAndQueueInsertion

    A Generic AddAttribute Method

    There are 2 attributes which this plugin adds to various parts of the target class.

    The DataContract attribute is to be added to the class itself. Then we need to iterate through the properties on the class, and add the DataMember attribute to each of those.

    In order to make this as easy as possible, I decided to create a utility method capable of quickly adding a named attribute to any given LanguageElement.

    AddDataContractAddAttribute

    In the method above, an ElementBuilder is used to create the Attribute and then the AttributeSection. For those that don’t know the AttributeSection is the pair of square brackets that the attribute sits inside. (These are angle brackets in VB.Net).

    As before, code is then generated and queue an insert into the ActiveTextDocument at the correct location.

    Putting it all Together

    All of this is drawn together in the body of the apply method.

    AddDataContractWrapInSingleStep

    First we add the System.Runtime.Serialization namespace. Next we decorate the class with the DataContract attribute. Then we iterate through all the properties of the class decorating each of these with the DataMember attribute. We call ApplyQueueEdits to apply each of the queued operations to the document in a single step.

    Finally we reparse the document and call the FormatFile action to perform any additional reformatting that might be necessary.

    Full source code is available

    As usual, the full source code for this plugin is available on github for your perusal.

    Feel free to fork (or just plain copy) the code for your own plugins and see what you can do with it.

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