BOO语言和基础 5
Boo is an object-oriented, statically typed programming language for the Common
Language Infrastructure (CLI) with a Python-inspired syntax and a special focus on
language and compiler extensibility. It’s this focus on extensibility that makes it ideally
suited for building DSLs.
Boo is not just a CLR language; it’s also a JVM language–BooJay
特点
BooManifesto.pdf
Ø Syntactic sugar for common programming patterns
Ø Automatic variable declaration and type inference
Ø Automatic typecasting
Ø Duck typing
http://boo.codehaus.org/Language+Guide)
Boo能干哪些事的参考
http://docs.codehaus.org/display/BOO/Useful+things+about+Boo
关键特性
Boo’s language-oriented features
Ø String interpolation
name = "dear reader"
print "Hello ${name}"
Ø Is, and, not, and or
customer.CurrentPlan is null and customer.RegisteredAt>SixMonthsAgo
Ø Optional parentheses
SuggestRegisterToClub("Preferred")
SuggestRegisterToClub "Preferred"
Ø Anonymous blocks
ints = GetListOfIntegers()
ints.ForEach do(i): print i
或
ints.ForEach:
print "foo"
Ø Statement modifiers：turn several statements into a single sentence有：if, unless, and while.
ApplyDiscount(0.5) if customer.IsPreferred
apply_discount_of 0.5 if customer.IsPreferred
Ø Naming conventions
multiple names for a single method is to extend the Boo
compiler in such a way that it automatically translates from one naming convention to
the other
Ø Extension methods
System.String:
classStringExtensions:
[Extension]
staticdefToPascalCase(str as string):
returnchar.ToUpper(str[0]) + str.Substring(1)
使用
importStringExtensions
"some string".ToPascalCase()
Ø Extension properties
classListExtensions:
[Extension]
static Length[list as IList]:
get:
returnlist.Count
importSystem.Collections
importListExtensions
a = ArrayList()
printa.Length
Ø The IQuackFu interface
If it walks like a duck and it quacks like a duck, then it must be an IQuackFu.
Otherlanguages call it duck typing or method missing (or message not understood) and
many dynamic languages support it.
Duck typing basically means that you don’t care what the actual type of an object is.
As long as it supports the operations you need (as long as it walks like a duck), you can
treat it as a valid object (it is a duck).
Rails’ ActiveRecord:
user as User = Users.FindByNameAndPassword("foo", "bar")
That will be translated by the compiler to this:
user as User = Users.QuackInvoke("FindByNameAndPassword", "foo", "bar")
Boo interactive shell
Boo interactive shell by just entering booish.exe
Boo interpreter
booi test1.boo
Boo compiler
booc test1.boo
http://home.comcast.net/~brent.hughes/BooWho.htm
控制语句结构
if<BooleanExpression>:
<StatementBlock>
elif<BooleanExpression>:
<StatementBlock>
<moreelif's>
else:
<StatementBlock>
while<BooleanExpression>:
<StatementBlock>
for<Variable> in <RangeOrSequence>:
<StatementBlock>
List Array Hash
a = [4, 9.82, "Help"]
MyArray = (3, 5, 7, 9)
MyStrArray = ("one", "two", "three")
MyHash = { "Susan":3, "Melanie":9, "Cathy":27 }
关于DSL 可以参考前面的几个文章
