Assume I have a Manipulate with two dynamic variables and I want to put the corresponding controls in a Row for aesthetics reason. I can think of two ways to do it as follows:
Row[Control/@{{{a,a_in},a_min,a_max},{{b,b_in},b_min,b_bmax}}]
or
Row[{Control[{{a,a_in},a_min,a_max}],Control[{{b,b_in},b_min,b_bmax}]}]
The issue is that in the first case after the 1st run of the cell containing Manipulate with that line the variables a, b become having defined value (a_in and b_in) respectively and for further evaluation are not recognized as variables of Manipulate, while in the other case a and b remain undefined and serve correctly as dynamic variables.
I expect that the Map (/@) somehow changes the order of evaluation in the expression and that the variable "leaks" outside the Row, gets told by Manipulate to have a value and takes it on. While on the other hand the simple Control[] correctly encloses a control option and nothing "leaks". Yet I find this claim possibly false and unsatisfyingly vague (thus hard to generalize and understand Mathematica better, which I would like to).
Can someone explain why that happens or point me to some other insightful answer (I guess this is not the first time this issue came up, but I can't form a proper query to google for it.)?