Ruby Basic types, dynamic features, code blocks

#Ruby Built-in basic data type Nilclass,tureclass,falseclass,time,date,string,range,struct,array,hash#Numerice 1. Divided into Interger integer class. Interger is divided into Fixnum and bignum. #2. #Float浮点数#3.Complex plural. #dynamic characteristics of Bury#1. Dynamically execute code eval in string form#2. Dynamically obtain the values of constants and variables in a module or class#3. Dynamically add a method to a class or object#4. Dynamic processing of known variables and methods#5. Dynamic Delete definition#Eval compiles and executes the string. The eval of JavaScript=Beginclass_eval The string as a code compilation within the context of the class Module_eval executes the string as code in the context of the class or module Instance_eval is compiled in the context of the instance =EndclassString PI="FJSKDJF"  defdosome (n) self[0,n]+ (Self.size > n?)"..":"")#spaces cannot be ignored =_=| |End forIinch[5,6,7,8] Module_eval"def Dosome_#{i}Dosome (#{i})End"endendputs"SDFSDF". Dosome_5puts"SDFDSFSDF". Dosome_6puts"GSFSDF". UpCase puts"SDFSDF". Send ("upcase")#method of the Send method to invoke the object dynamically#puts "SADFD". Methods#puts String.methods #获取对象的所有方法名#Instance_methods Returns all exposed instance method names, Protected_methods returns the protected method namePuts string.method_defined? (: UpCase)#checks whether an instance method is defined by an objectPuts"String". respond_to? (: UpCase)#checks whether an object can be matched to a call to an instance methodPuts String.const_get ("PI")#gets the value of a constant in a module's class based on the name of the constantputs String::P i#The const_missing,method_missing method allows you to customize the returned error message when an object calls a method or constant that does not exist. Array=[1,3,4,5,22,33]array<<[1,44,5,6,7]#adding elementsArray.push ([333,1234,1233333])#adding elementsArray.each {|item|puts item}

Lambda and Proc,block

defTest (arg,arg2,&block)#parameters passed to the code block after processing the parameters of the method  yieldARG+ARG2,"the second parameter of a code block"#takes up two bits, so the following call will output 2 times, and the code block is actually a proc object  yieldARG+ARG2,"a second parameter"#The yield here is actually quite similar to the following functionBlock.call (ARG+ARG2,"The second argument of the proc object") End#Test (one) {puts "yield placeholder"}#Test do#puts "Today is a good day."#End#two ways to create code blocks {code}, do code endTest"what thing?","Entebbe") {|x,y| puts x+Y}block=proc.new{|o,x| puts o+x+"proc Method"}test ("What, what?","Regular Army",&block)#the parameters of the code block are passed with the | parameter | Yield (x, y) pass parameters to code blocks#the advantage of using the Proc method is that you can feel the code block argument passed to the method, and the Proc object does the method pass with the & symboldefF0 () p= proc.new {return0} p.call1EnddefF1 () L=Lambda{return0} l.call1endf0#returns 0F1#returns 1#If you can understand that proc is more like block,lambda in behavior than it is simply anonymous, then you won't be surprised by the results above. #If you make some changes to the F0,F1, it will be easier to understand the results above. defF0 ()return01EnddefF1 ()def __f1    return0 End__f11endf0#returns 0F1#returns 1

Exception handling

def extest (x, y)  begin#try  z=x/y  =>err#catch      puts err     #retry redo  ensure#finaly  " operation complete "  end  endextest (1,0)

Ruby Basic types, dynamic features, code blocks