BuilderWithConditionalException
From APIDesign
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=== Throw on I/O Error === | === Throw on I/O Error === | ||
| - | The builder pattern delays reading of the actual file up until the ''build()'' method is called. As reading of a file means an I/O operation and as each I/O operation in Java may yield [[checked exception]] {{JDK|java/io|IOException}}, it is desirable for the ''build()'' method to propagate it to the caller. | + | The builder pattern delays reading of the actual file up until the ''build()'' method is called. As reading of a file means an I/O operation and as each I/O operation in Java may yield [[checked exception|checked]] {{JDK|java/io|IOException}}, it is desirable for the ''build()'' method to propagate it to the caller. |
Revision as of 13:23, 10 June 2016
The builder pattern is gaining more and more popularity in the APIs that I design: In Truffle API we are trying to use it a lot. For example an instance of the PolyglotEngine is constructed via a builder obtained from its newBuilder() method.
Builder for Source
These days I am trying to use the builder pattern also for construction of Source. Rather than having various (and overloaded) methods with fromFileName, etc. we'd like to have:
Source source = Source.newFromFile(file). mimetype("text/javascript"). name("FancyName.js"). build();
It works fine and allows the users to specify only those properties that are needed - for example one can omit the name - then it would be derived from the name of the file. The same applies to mimetype.
Throw on I/O Error
The builder pattern delays reading of the actual file up until the build() method is called. As reading of a file means an I/O operation and as each I/O operation in Java may yield checked IOException, it is desirable for the build() method to propagate it to the caller.
Follow
