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evaluates a + b when lv is first called/used, and saves the value, so that it is only computed once.
Use Typed Equality
Subtle bugs can arise when comparing a == b, when a and b turn out to be different types. The == operator is "natural" equality, which simply returns false if a and b are different types.
There are arguments for why this is good and useful and such, see: http://www.artima.com/pins1ed/object-equality.html.
However, very often this masks a programmer error. If a and b are of types that it makes no sense to be comparing, then a == b should, ideally, be a scala compile-time type error.
To achieve this, we have two forms of strongly typed equality in the daffodil.equality package. To use them you must
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import edu.illinois.ncsa.daffodil.equality._ |
There are two operators:
- a =:= b provides "Type Equality" for use when a and b have a subtype relationship, including the most obvious case of a and b both being of the same type.
- a =#= b provides "View Equality" for use when a and b are convertible, that is, a can be implicitly converted to b's type, or b can be implicitly converted to a's type. Numbers and number-like types are common cases for this so the "#" in the operator is suggestive of "number"
Of these, the a =:= b is the more important and more commonly used. The ":" in the name is supposed to suggest the concept of "typed".
(To be determined - what is the performance of these relative to ordinary a == b.)
Attach the Source Code
Our build system will obtain the source code for libraries when sbt is able to retrieve them. If a library is not sbt-managed the library itself goes in the lib sub-directory, and the source code and documentation go into libsrc.
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