heitml 1 Compatibility

heitml 2.1 includes the non-object-oriented heitml 1.x libraries for compatibility. This chapter contains the library documentation and a lot of demonstration/example programs.

If you prefer programming heitml in a non-object-oriented way, these libraries and demos might still be interesting to you.

To use the heitml 1 libraries, please put the lib1.2 directory into your include path, and set the configuration option lib to off.

Incompatibilities of the heitml language

In heitml 1, a define without formal parameters accepted any possible actual parameters. In heitml 2, it does not accept any parameters. To accept any possible actual parameters, the '...' syntax can be used. To fall back to the heitml 1 behavior, set the compat configuration option to 1.

In heitml 1, the "Q" format of the ? Tag converted empty strings to null within a query. heitml 2 does this conversion only if the compat configuration option is set to 1.

In heitml 1.23, the undocumented directory() function returned an empty tuple on a non-existing directory. In heitml 2, it returns the null value to distinguish between a non-existing directory and an empty existing directory.

heitml 2 does shortcut evaluation of conditionals. Therefore, you should review heitml 1 programs that have side effects in conditionals.

In heitml 1, the null value behaved neutral in expressions (e.g. null+1000 evaluated to 1000). heitml 2 returns an error for expressions operating on null.

In heitml 1, comparing two values with operators == or != resulted in type errors, if operand types were incompatible. heitml 2 returns false (see Language Reference).

In heitml 1, the configuration option memlimit value was specified in Megabytes. With heitml 2, it is specified in Kilobytes.

In heitml 1, you were able to pass undefined operands as well as function calls to the default() function. With heitml 2, you should assign the result of each function call to a variable first and pass this variable to the default() function.