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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: nested macros [was: RE: AW: apostrophes, quotation marks, left or right quotes?] |

Date |
Tue, 26 Feb 2008 14:58:43 -0000 |

Nesting I find easiest to understand by analogy with parenthesised expressions in elementary algebra. Thus we are all taught (I presume!) to evaluate expressions like (2 / (3 + 5)) from the inside outwards, so (3 + 5) is evaluated first, giving 8 and then 2/8 = 1/4. Similarly, in `x`i'' the `i' must be evaluated first. The same principle applies to triple and higher order nesting, which are in practice pretty rare. The rule is thus simply: work from the inside outwards. A basic tutorial on macros is included within SJ-2-2 pr0005 . . . . . . Speaking Stata: How to face lists with fortitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox Q2/02 SJ 2(2):202--222 (no commands) demonstrates the usefulness of for, foreach, forvalues, and local macros for interactive (non programming) tasks The slides for a talk version of that paper can be found in various places, e.g. at http://www.cpc.unc.edu/services/computer/presentations/statatutorial/cox _article.pdf Nick n.j.cox@durham.ac.uk Martin Weiss [...] the real hurdle is to understand the macro expansion process induced by the left and right quotes. To my - possibly limited - knowledge, there is no single place where you can learn it satisfactorily. In particular, the nesting mentioned by Nick has given me headaches too many times. In fact, I still use a trial-and-error process, coupled with -set trace on- (and the concomitant cluttered screen) to figure it out in complicated cases... * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: AW: apostrophes, quotation marks, left or right quotes?***From:*Martin Weiss <martin.weiss1@gmx.de>

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