The resulting font is not determinstic

[timdream]

Every make generates different bits. Not sure if we want to fix it.

[jfkthame]

The OpenType format includes 'created' and 'last modified' timestamps in the 'head' table. I expect these will be set to the time the font is generated, and therefore will be different on every build.

(And this will in turn result in a couple of checksum differences.)

My guess is that's the only difference, but it might be worth checking... if you use TTX to dump the font to XML format, you can then diff two versions and see whether anything besides the timestamps and checksums actually changes.

[timdream]

Thanks for the pointer! You have guessed it correctly:

$ diff a.xml b.xml
12372c12372
<     <checkSumAdjustment value="0x74dbf5bf"/>
---
>     <checkSumAdjustment value="0x74dbf325"/>
410742c410742
<     <sourceModified value="Mon Nov 21 08:40:46 2016"/>
---
>     <sourceModified value="Mon Nov 21 08:46:19 2016"/>

So this timestamp is simply the time on my computer. I am not entirely sure it's usefulness, but I don't think it make sense to freeze it...