理解 App 升级

This guide explains how to manage upgrades of Sencha Cmd and Sencha frameworks in your applications.

Prerequisites

The following guides are recommended reading before proceeding further:

• Sencha Cmd 介绍.
• Using Sencha Cmd.

Upgrading Your Application

Generated applications include two basic kinds of content relevant to Sencha Cmd: build scripts (or scaffolding) and the important content of the target Sencha SDK’s. As such, you will occasionally need to upgrade these pieces. You can do this with the following command:

sencha app upgrade [ path-to-new-framework ]

The “path-to-new-framework” is optional and is used to upgrade both the Sencha Cmd scaffold and the framework used by the application.

Preparing to Upgrade

When performing any bulk operation on your application source code, it is highly advisable to start in a “clean” state with respect to version control. That is, it is best to have no uncommitted changes before performing the upgrade. This way, you can easily review and possibly discard changes made by sencha app upgrade with minimum trouble.

Upgrading The Sencha Cmd Scaffold

To bring up a new version of Sencha Cmd with your application produced by a previous version, you can run this command from inside your application:

sencha app upgrade

This will replace the content of ".sencha" but will also upgrade "app.js" as well as a handful of other files.

Upgrading Frameworks

Since generated applications include their own copies of the SDK from which they were originally generated, applications need to be updated to use a new version of the SDK. The sencha app upgrade command will replace the old SDK copy with the new one:

sencha app upgrade ../path/to/framework

The above command points to the path to a downloaded and extracted SDK.

Important. Do not use the -sdk switch for this command as you would for the sencha generate app command. Instead use the command shown above.

There may also be some changes made to generated source code if you are upgrading from Ext JS 4.1 to 4.2+.

Dealing With Merge Conflicts

In Sencha Cmd, the code generator incorporates a 3-way merge to best reconcile the code it generates with the code it generated last time and the current state of the code as you may have edited it. This approach allows you to edit files (like "app.js") in many ways so long as your changes don’t overlap those that Sencha Cmd wants to make.

The merge process follows this pseudo-code for "app.js" (as an example):

mv app.js app.js.$old
regenerate last version to app.js.$base
generate new version to app.js
diff3 app.js.$base app.js.$old app.js

In the ideal scenario, you won’t notice this mechanism at work. There are situations, however, in which you may receive an error message telling you there was a “Merge conflict” and that you need to resolve this manually.

In cases where the base version cannot be recreated, the ".$old" file is left on disk and you can compare it to the current version. Or you can use your source control system to compare the current file to what was last committed.

When the base version could be produced (the majority case), the ".$old" file is deleted because the conflicts are annotated in the target file in the standard way:

<<<<<<< Generated
    // stuff that Sencha Cmd thinks belongs here
=======
    // stuff that you have changed which conflicts
>>>>>>> Custom

Using Visual Merge Tools

This process exactly matches what you might expect in a source control system for a file that you and another user (in this case, Sencha Cmd) have both modified. As with version control, the ideal way to resolve these issues is with a visual merge tool.

To configure Sencha Cmd to invoke a merge tool when it encounters merge conflicts, you need to set the following two properties:

cmd.merge.tool
cmd.merge.tool.args

Setting the cmd.merge.tool property can be as simple as a program name if that program is in the PATH, but otherwise, it may need to be the full path to the executable.

The corresponding cmd.merge.tool.args property should be set according to the command line arguments needed by the desired merge tool. This property is a template that can contain the following replacement tokens:

cmd.merge.tool.args={base} {user} {generated} {out}

The template is first split on spaces then the tokens are replaced by actual files names. If the merge tool has more custom needs, it may be necessary to set cmd.merge.tool to a shell script that can wrap the merge tool.

Merge Tool Helper Properties

Sencha Cmd provides properties to help configure several popular merge tools:

For p4merge you can set these properties like so:

cmd.merge.tool=p4merge
cmd.merge.tool.args=${cmd.merge.tool.args.p4merge}

This assumes that "p4merge" is in your PATH environment variable. If not, you will need to fully specify the path to the executable.

For SourceGear:

cmd.merge.tool.args=${cmd.merge.tool.args.sourcegear}

For kdiff3:

cmd.merge.tool.args=${cmd.merge.tool.args.kdiff3}

For Syntevo SmartSynchronize 3:

cmd.merge.tool.args=${cmd.merge.tool.args.smartsync}

For TortoiseMerge (part of TortoiseSVN):

cmd.merge.tool.args=${cmd.merge.tool.args.tortoise}

For AraxisMerge:

cmd.merge.tool.args=${cmd.merge.tool.args.araxis}

Alternative Strategies

If you have heavily customized your application, it is sometimes simpler to just generate a new application in a temporary location and start by copying its ".sencha" folder to replace your own, being careful to reconcile any changes you may have made and incorporate them in the new version.

If you are using a workspace, you may need to copy the ".sencha/workspace" folder from the generated app to your workspace’s ".sencha" folder to replace the old version there.

Next Steps

• 对编译器友好的代码原则
• Sencha Cmd 包(Packages)
• Sencha Cmd 的 Workspace
• Sencha Cmd 进阶