Page 7: Summary

[ashimo]

TRY 5 Summary

Reading and writing data from/to a file

Step 1. Specifying the location of a file

Code:

let location_variable_name:Url = {url “path to file location”}

Step 2. Opening file as a Stream

• TextInputStream (read)
  
• TextOutputStream (write)
  

Code:

let stream_variable_name:TextInputStream = {read-open location_variable_name}
let stream_variable_name:TextOutputStream = {write-open location_variable_name}

Step 3. Using methods to read or write data

• Methods such as read-line or write-one-string
  

Step 4. Closing the file

Code:

{if-non-null stream_variable_name then
    {stream_variable_name.close}
}

Repeat Expressions

until expression (processing repeats until conditional expression is true)

Code:

{until conditional_expression do
    body
}

for expression (specifying a range)

Code:

{for repeat variable:int = initial_value to final_value step step_size value do
    body
}

As well as to, there are also the below, downto, and above keywords. The step_size can be omitted when the desired step_size is 1.

for expression (repeats only the values among the elements of a collection, such as an array)

Code:

{for element_variable:element_type key key_variable[:key type] in (collection) name do
    processing
}

Note that element_variable:Element_type or key key_variable: key_type can be omitted.

Exception Processing

Code:

{try
    Processing in which an exception may occur.
catch exception_variable_name: exception
    Exception Processing
finally
    Processing that must be performed regardless of whether an exception occurs
}

The catch and finally clauses can be omitted. Also, each try can be declared more than once.