[英]Is it possible to define a block with default arguments in Ruby?
这个问题涉及传递给Ruby块的可选参数。 我想知道是否还可以使用默认值定义参数,以及语法是什么。
乍一看,答案似乎是“否”:
def call_it &block
block.call
end
call_it do |x = "foo"|
p "Called the block with value #{x}"
end
...结果是:
my_test.rb:5: syntax error, unexpected '=', expecting '|'
call_it do |x = "foo"|
^
my_test.rb:6: syntax error, unexpected tSTRING_BEG, expecting kDO or '{' or '('
p "Called the block with value #{x}"
^
my_test.rb:7: syntax error, unexpected kEND, expecting $end
end
^
ruby 1.9允许这样做:
{|a,b=1| ... }
穷人的默认块参数:
def call_it &block
block.call
end
call_it do |*args|
x = args[0] || "foo"
p "Called the block with value #{x}"
end
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