TExpressionColumn crashes with spaces in column name

[De-Novo-Research]

The following code crashes

  var di:=TDataItem.Create;
  di.AsTable:=True;
  di.Items.Add('First column',dkInt32);
  di.Items.Add('Second column',dkInt32);

  di.Append([1,2]);

  di.Items.Add(TExpressionColumn.From(di,'First column / Second Column',True,'Ratio'));

It is finding a space after 'First' in the expression and trying to find a column called First.
I tried putting quotes around the column names in the expression

di.Items.Add(TExpressionColumn.From(di,'"First column" / "Second Column"',True,'Ratio'));

and then got

[davidberneda]

The chosen delimiter is brackets {First Column}
This was decided because some database (sqlite I think) allows double quotes in field names.

TExpressionColumn.From(di,'{First column} / {Second Column}',True,'Ratio');

It would not be difficult to offer customization, for example:

TExpression.Delimiter := TExpressionDelimiter.DoubleQuote;

and then parsing will use that as delimiter.

I don't remember if escaping was implemented, ie: \"

[davidberneda]

There is another problem, as the expression is "/" (division), the resulting data type should be promoted to single or double to accomodate decimals.
Right now it is forcing the type to int32 (the types of the expression operands) so the resulting 1/2 is zero instead of 0.5

Just fixed.

[davidberneda]

Reviewing the code, double or simple quotes cannot be used as field name delimiters because quotes are reserved to accept strings in expressions, ie:

TExpressionColumn.From(di,'{My column} + "Hello" ',True, 'Foo' );

"Hello" here is just a string, not a column name.

[De-Novo-Research]

How do you guys do the documentation. I am thinking of creating a fork in git and adding documentation to the methods/units as I go along. Would you accept pull requests if I do this? Can you use this to generate your CHM/web documentation. What if I want to create useage examples. Of course I can do this in the XMLdoc in the method signature and that is fine for very simple things, but rapidly gets verbose. Should we use .md files somehow. Can your tool pull in .md files into the CHM?