FAQ

SPVM FAQs.

Backward Compatibility

Backward Compatibility

License

Why was the license of SPVM changed to the MIT license?

Because the MIT license is the open source license that most developers know and understand.

The Perl Artistic License is a great open source license, but its biggest problem is that it is not well known outside of Perl developers.

Syntax

What is the advantage the local variable name has sigil($)?

Because the local variable name ($foo) has a sigil, it will not conflict with keyword names, class names, method names, or field names.

When declaring local variables, you can write programs without worrying about name conflicts.

You can write programs without worrying about name conflicts with keywords that may be added in the future.

Class variable names will conflict with local variable names, but this can be conventionally avoided by using upper case for class variable names($FOO) and lower case for local variable names($foo).

String

What is the character code of the SPVM string?

The SPVM string are simply a sequence of bytes of the string type. The sequence of bytes is exactly the same as the byte[] type.

A string are supposed to be represented in UTF-8, which is just a sequence of bytes.

Please tell me about the conversion between a Perl string and a SPVM string.

A Perl string is converted to a SPVM string by the new_string method in the SPVM::ExchangeAPI class.

Whether the UTF-8 flag is set in the Perl string or not, the sequence of bytes stored in the PV slot of Perl's SV type is copied to the SPVM string.

A SPVM string is converted to a SPVM::BlessedObject::String object when is is returned to Perl.

A SPVM::BlessedObject::String has the SPVM string as it is.

If you want to convert it to a Perl string with UTF-8 flag, use the to_string method in the SPVM::BlessedObject::String class or use "" overloading, like "$blessed_object_string". The utf8::decode function is called and the UTF-8 flag is set to the Perl string.

If you want to treat it as a sequence of bytes, use the to_bin method in the SPVM::BlessedObject::String class.

System Calls

What are the system calls used in the SPVM distribution?

The system calls used in the SPVM distribution are the following ones.

In the SPVM language, the print operator calls a system call of stdout. The warn operator calls a system call of stderr.

The modules contained in the SPVM distribution do not call any system calls.

The methods for system calls are implemented in SPVM::Sys distribution.