Author: limpbizkit
Date: Thu Jan 1 15:51:04 2009
New Revision: 775
Added:
wiki/AvoidConditionalLogicInModules.wiki
Log:
Created wiki page through web user interface.
Added: wiki/AvoidConditionalLogicInModules.wiki
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+++ wiki/AvoidConditionalLogicInModules.wiki Thu Jan 1 15:51:04 2009
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+=Avoid conditional logic in modules=
+It’s tempting to create modules that have moving parts and can be
configured to operate differently for different environments:
+{{{
+public class FooModule {
+ private final String fooServer;
+
+ public FooModule() {
+ this(null);
+ }
+
+ public FooModule(@Nullable String fooServer) {
+ this.fooServer = fooServer;
+ }
+
+ @Override protected void configure() {
+ if (fooServer != null) {
+
bind(String.class).annotatedWith(named("fooServer")).toInstance(fooServer);
+ bind(FooService.class).to(RemoteFooService.class);
+ } else {
+ bind(FooService.class).to(InMemoryFooService.class);
+ }
+ }
+}
+}}}
+Conditional logic in itself isn't too bad. But problems arise when
configurations are untested. In this example, the`InMemoryFooService` is
used for development and `RemoteFooService` is used in production. But
without testing this specific case, it's impossible to be sure that
`RemoteFooService` works in the integrated application.
+
+To overcome this, *minimize the number of distinct configurations* in your
applications. If you split production and development into distinct
modules, it is easier to be sure that the entire production codepath is
tested. In this case, we split `FooModule` into `RemoteFooModule` and
`InMemoryFooModule`. This also prevents production classes from having a
compile-time dependency on test code.
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