Is This Solution for Caches vs Cookies Going to Get Me in Trouble?

ck_macleod_ignoredThis post consists of a a question I posed at StackExchange/”WordPress Development,” relating to the Commenter Ignore and Commenter Highlight Buttons plug-ins that I’ve been working on (debuting at this site in unfinished form, as of this writing). Won’t likely be of any interest to non-developers!

I’ve come up with a provisional solution for a not exactly common, but far from unprecedented problem with the interaction of popular WP caching solutions with cookies, in this case the standard WP comment cookies. My solution also bears on the rarely well-defined “known users” exception to serving cached files. Whether what I stumbled upon is usable or not, I figure that explaining it and possibly learning why it’s a bad idea might be generally instructive.

I’ve tested my method with WP Super Cache, W3 Total Cache, and Comet Cache. The one that I broke down for myself in detail while studying this problem was WP Super Cache (“WPSC” hereafter), so I’ll use it as my main example.


When a WP standard comment thread is set to allow visitors to comment, comments cookies are set for any commenter who is not a registered user and logged in, with actual commenting privileges subjected to further checks. In what I believe is the most common configuration, a commenter needs to supply only a name and an email address. These are stored within two browser cookies, usually comment_author_ . COOKIEHASH, and comment_author_email_ . COOKIEHASH. COOKIEHASH is defined according to user options.

If set to deliver freshly generated files to “known users,” WPSC determines whether or not to serve a cached file on the basis of several checks: Logged-in users get fresh files, and so do visitors “who can comment.” The latter are chiefly identified by the presence in their browsers of comment_author_ cookies which are not specifically or uniquely identified for the particular user by the COOKIEHASH (usually but not always an MD5-encoded version of the “siteurl” recorded in site options).

What appears to be the key part of the WPSC code, from wp-cache-phase1.php LL371-383, uses a RegEx pattern to get a string, cycling through the cookies:

Now, if I were working strictly in PHP, I could re-produce or hook into WP core functions, and get the normal comment_author_ . COOKIEHASH set by the comment template, but I am working in jQuery using the jQuery Cookie plug-in. However, as you can see if you look at the RegEx, the WPSC function doesn’t care about the COOKIEHASH: It’s satisfied if it encounters comment_author_.


$.cookie( 'comment_author_proxyhash', 'proxy_author', { path: '/' } );

For those unfamiliar with jQuery Cookie: The above sets a simple session cookie with key = comment_author_proxyhash and value = proxy_author, good for the entire site. (Also, for those who use jQuery Cookie and WP, in addition to pre-substituting the familiar jQuery $ for the WP jQuery, I’ve also already set $.cookie.raw = true;.)

I added the line to my jQuery script, and, *voila!*, WPSC, W3 Total Cache, and Comet Cache are all acting like I want them to. After I use the script, and reload, I get fresh pages. If I happen to place a real comment, the normal comment_author_ and comment_author_email_ cookies are set, and there doesn’t seem to be any problem with co-existence.

Perhaps one defect would be that the “proxyhash” cookie will travel with the user as long as he or she keeps the session open, but that doesn’t strike me as likely a major problem – or even worth a warning. I’ve certainly never heard of someone complaining about such a thing happening with one of the regular cookies.

But maybe there’s something I’m missing, and about to discover much to my woe, if potentially to my edification as well. Or maybe there’s a relatively simple best-practicey way for me to replicate the COOKIEHASH in jQuery, also covering alternative use cases… or to achieve the same end effect by other means – other ways of tricking the caching plug-ins into treating the visitor as a commenter…

If not, is there any good reason NOT to push this or something close to it out to the universe in a plug-in?

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Writing since ancient times, blogging, e-commercing, and site installing-designing-maintaining since 2001; WordPress theme and plugin configuring and developing since 2004 or so; a lifelong freelancer, not associated nor to be associated with any company, publication, party, university, church, or other institution. 

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Noted & Quoted

TV pundits and op-ed writers of every major newspaper epitomize how the Democratic establishment has already reached a consensus: the 2020 nominee must be a centrist, a Joe Biden, Cory Booker or Kamala Harris–type, preferably. They say that Joe Biden should "run because [his] populist image fits the Democrats’ most successful political strategy of the past generation" (David Leonhardt, New York Times), and though Biden "would be far from an ideal president," he "looks most like the person who could beat Trump" (David Ignatius, Washington Post). Likewise, the same elite pundit class is working overtime to torpedo left-Democratic candidates like Sanders.

For someone who was not acquainted with Piketty's paper, the argument for a centrist Democrat might sound compelling. If the country has tilted to the right, should we elect a candidate closer to the middle than the fringe? If the electorate resembles a left-to-right line, and each voter has a bracketed range of acceptability in which they vote, this would make perfect sense. The only problem is that it doesn't work like that, as Piketty shows.

The reason is that nominating centrist Democrats who don't speak to class issues will result in a great swathe of voters simply not voting. Conversely, right-wing candidates who speak to class issues, but who do so by harnessing a false consciousness — i.e. blaming immigrants and minorities for capitalism's ills, rather than capitalists — will win those same voters who would have voted for a more class-conscious left candidate. Piketty calls this a "bifurcated" voting situation, meaning many voters will connect either with far-right xenophobic nationalists or left-egalitarian internationalists, but perhaps nothing in-between.

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Understanding Trump’s charisma offers important clues to understanding the problems that the Democrats need to address. Most important, the Democratic candidate must convey a sense that he or she will fulfil the promise of 2008: not piecemeal reform but a genuine, full-scale change in America’s way of thinking. It’s also crucial to recognise that, like Britain, America is at a turning point and must go in one direction or another. Finally, the candidate must speak to Americans’ sense of self-respect linked to social justice and inclusion. While Weber’s analysis of charisma arose from the German situation, it has special relevance to the United States of America, the first mass democracy, whose Constitution invented the institution of the presidency as a recognition of the indispensable role that unique individuals play in history.

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[E]ven Fox didn’t tout Bartiromo’s big scoops on Trump’s legislative agenda, because 10 months into the Trump presidency, nobody is so foolish as to believe that him saying, “We’re doing a big infrastructure bill,” means that the Trump administration is, in fact, doing a big infrastructure bill. The president just mouths off at turns ignorantly and dishonestly, and nobody pays much attention to it unless he says something unusually inflammatory.On some level, it’s a little bit funny. On another level, Puerto Rico is still languishing in the dark without power (and in many cases without safe drinking water) with no end in sight. Trump is less popular at this point in his administration than any previous president despite a generally benign economic climate, and shows no sign of changing course. Perhaps it will all work out for the best, and someday we’ll look back and chuckle about the time when we had a president who didn’t know anything about anything that was happening and could never be counted on to make coherent, factual statements on any subject. But traditionally, we haven’t elected presidents like that — for what have always seemed like pretty good reasons — and the risks of compounding disaster are still very much out there.

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